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Elements of Drawing 



L BY 



GEORGE Fi 'BLESSING, M.E., Ph.D. 

Professor of Mechanical Engineering and in charge of Engineering, Swarthmore College 
Formerly Assistant Professor of Machine Design, Cornell University 

AND 

LEWIS A. DARLING, E. in M.E. 

Engineering Department Remy Electric Co., Formerly Assistant Professor of 
Machine Design, Cornell University 



FIRST EDITION 

FIRST THOUSAND 



NEW YORK 

JOHN WILEY & SONS 

London: CHAPMAN & HALL, Limited 

1912 






Copyright, 1912, 

BY 
GEORGE F. BLESSING and LEWIS A. DARLING 



Stanbope ipress 

F, H.GILSON COMPANY 
BOSTON, U.S.A. 



^ ^ 



£CU320111 



I 



PREFACE 

It is the purpose of this book to present a course of instruc- 
tion in Mechanical Drawing for beginners who intend to pursue 
a course in engineering or who desire to prepare themselves to 
do commercial drafting. The work herein outlined, as well as 
that contained in the companion volume, "Elements of De- 
scriptive Geometry" by the same authors, is based on the 
drawing-room courses required of all first-year students in 
Mechanical and Electrical Engineering in Sibley College, Cornell 
University, as a preparation for the more advanced work of 
design in the second and third years of the course, which is also 
required of all students in the college. 

The task of writing the book and its companion volume was 
undertaken by the authors, at the writer's request, while they 
were members of the staff of instruction of the Department of 
Machine Design and Construction of Sibley College. The object 
in view was twofold, namely, to obtain a book exactly suited to 
the needs of the Department, which we had heretofore been 
unable to do ; and also to put into permanent shape the methods 
and principles used in this work, thus forming one of a correlated 
series of texts which eventually, it is expected, will fully cover 
the entire work of the department. The authors brought to 
the task a full knowledge of the more advanced work of the 
Department, having had experience in teaching these advanced 
subjects in design which, with their experience elsewhere both in 
practical and teaching positions, was of great aid in improving 
and refining this more elementary work. 

There is nothing experimental in the principles or methods 
outUned in the book, as most of them have been in constant use 
in Sibley College for years and have been productive of most 
excellent results, not only in teaching the art of mechanical 
drawing but as a preparation for the more advanced work in 
design. 



VI PREFACE 

Particular attention is given in the drawing-room work in 
Sibley College to the art of lettering and the methods presented 
in the chapter on lettering have been remarkably successful. 
Only two alphabets have been presented, it being considered 
best to confine the student's efforts to a thorough study and 
practice of those two which are of almost universal use rather 
than to make a superficial study of more elaborate alphabets 
which find very limited, or no use. The system of spacing was 
very largely developed by Prof. John T. Williams, who has 
taught it for a number of years with marked success. The authors 
have refined the system and also developed and presented a 
spacing chart, as it is believed that some instructors may prefer 
its use to that of rules. 

In regard to the material on "drawing-room system," no 
claim is made by the authors that it is the best in the sense that 
there is a best system, but it is their belief, which is based on 
considerable experience, that if this system is well understood 
by the student he will have no trouble in understanding any 
other he may be called upon to work with. 

Chapter V has been presented because of the growing popu- 
larity of isometric drawing in practically all branches of tech- 
nical work. 

It will be noted that though the book is based on the practice 
of Sibley College it is written in a flexible manner so as to be 
adaptable to almost any logical sequence of presentation, the 
general text matter applying equally to the drawing-board 
course presented or to a beginners' course arranged by in- 
structors in the subject. The following suggestions by the 
authors as to the use of this book will make this clearer. 

The text matter is intended to give in a practical and concise 
form such information as the beginner should have in order to 
intelligently pursue the drawing-board work. 

It is not supposed that lessons he assigned for recitation after 
the manner usually followed in teaching textbooks, that is, by 
beginning with Chapter I and assigning consecutive para- 
graphs to the end. The paragraphs should be assigned at the 
time the information can he applied directly to the drawing 
being executed. To facilitate this method each drawing plate 



PREFACE VU 

has certain paragraphs assigned and at the completion of the 
plate there should be an examination, oral or written, covering 
these paragraphs. The proper method of covering the text 
previous to examinations will depend upon the methods of the 
institution using the book. It is most desirable to have regular 
recitation periods, and the aiithors beheve one hour per week 
upon recitation should cover the work satisfactorily. Where 
this is impracticable the instructor should question the student 
as he proceeds with his work in the drawing-room. Especial 
attention should be directed to points where the student's work 
shows a lack of knowledge and he should be required to refer 
at this time to the parts of the text covering the points in ques- 
tion. 

Where the book is used in this manner, that is, simply as a 
book of reference, a preliminary examination should be held 
after the completion of each plate. The instructor should con- 
stantly keep in mind the object of this book, which is to teach 
the student: 

ist, how to select, care for, and use drawing instruments. 
2nd, how to make and read technical drawings. 
3rd, how to think over the drawing board. 
4th, to lead him to consider the relation drawing bears to 
design, shop processes, and shop organization. 

The third and fourth items are not usually given the attention 
their importance demands, and it is not unusual to see a college 
graduate make a beautiful drawing which is full of errors, due 
to the fact that all thought has been given to the drawing paper 
and none to the object it represents or to the shop methods 
necessary to produce this object. To aid in overcoming this 
dif&culty the authors have avoided the use of models of the 
geometric or kindergarten type or of machine parts selected 
at random. 

The models selected are parts of a wood-turning speed lathe, 
and are selected because the students will most likely be more 
famihar with this machine than any other. Also in most 
places where this course is taught the student will be working on 
his wood- turning exercises in the shop, on this machine, at about 



VIU PREFACE 

the same time he is doing his drawing. For this reason he is 
most apt to study the principles of design involved, the relation of 
parts, etc., and thus do his work in a much more intelligent 
manner than if he held no further interest in the model than 
that of making a dimensional picture of it. 

Dexter S. Kjmball, 
Professor of Machine Design and Construction, 

Cornell University. 
June 8, 1912. 

AUTHORS' NOTE 

The authors are deeply indebted to Prof. J. T. Williams of 
Sibley College, Cornell University, without whose assistance 
and cooperation this book in its present form would not have 
been possible. 

Grateful acknowledgment is also made of assistance by Prof. 
D. S. Kimball in developing the book and outlining its scope, 
and to Prof. G. W. Lewis, Messrs. A. Kessler and L. J. Brad- 
ford for assistance in preparing material and reading proof. 



CONTENTS. 



Page 

Frontispiece i 

Perspective View of Wood-turning Speed Lathe. — Partial Longi- 
tudinal Section through Headstock. — Partial Longitudinal Section 
through Tailstock. 

Preface v 

General Purpose of the Book. — Basis on which the Book is Planned. — 
Special Attention Given to Lettering. — Growing Popularity of Iso- 
metric Drawing. — Flexibility of the Book. — The General Text to be 
Referred to as Needed and Consecutive Text Lessons not to be Given. 
— Points to be Kept in Mind by the Instructor. — Models Selected for 
the Courses in Drawing are Parts of a Wood-turning Speed Lathe. — 
Author's Acknowledgment. 

CHAPTER I. 

Selection, Care and Use op Drawing Instruments and Materials. 

Sec. 

1. Introductory i 

Quahty of Instruments. — Care of Instruments. — Description of 
Instruments and Supplies. 

2. List of Instruments and Supplies Necessary for Complete Courses. . 2 

3. Drawing Paper 4 

Selection. — Quality. — Paper for Inked Drawings. — Paper for Pencil 
Drawings. — Working Side. — Detail Manila Paper. — Whatman Paper. 

4. Ruled Paper 5 

Purpose. — Cross-section Ruling. — Isometric Ruhng. — Cleaning Ruled 
Paper. 

5. Tracing Paper 6 

Description. — Blue Prints from. 

6. Tracing Cloth 6 

Description. — The Glazed Side. — The Dull Side. — Cutting Tracing 
Cloth to Size. — QuaUty to Use. 

7. Blue-print Paper 6 

Description. — Formula for Making Blue-print Paper. — Storage. 

8. Drawing Boards 7 

Material and Design. — Testing. 

9. Thumb Tacks 8 

Best Design. — Use of. 

ix 



X CONTENTS 

Sec, Page 

10. T-Squares 8 

Purpose. — Design and Materials. — To Test. — Care of. — Use of. 

11. Triangles lo 

Design and Materials. — Desirable Size. — Testing the Angles and 
Edges. — Use of. 

12. Irregular Curves 13 

Design and Materials. — Use of. 

13. Pencil Pointer 14 

Design and Use of. 

14. Lead Pencils - 14 

Essential Qualities. — Commercial Rating. — Design of. — Care of. — 

To Sharpen. — The Cone Point. — The Chisel Edge. — To sharpen Lead 
for Bow Pencil or Compass. 

15. Erasers and Erasures 16 

Purpose and Quality. — Method of Making Erasures. 

16. Erasing Shield 17 

Use and Design of. 

17. Soapstone 18 

Description and Use of. 

18. Drawing Ink 18 

Requirements of a Good Drawing Ink. — Colored Drawing Inks. — 
Care of. 

19. Ordinary Pens 18 

Description of Common Styles. — Ball-pointed Pen. — Crow-quill Pen. 

— Selecting a Pen. — "Breaking in" and Use of Pen. 

20. Pen Holders 20 

Design of. 

21. Ruling Pens 20 

Design and Materials. — To Adjust. — To Fill. — Proper Use of. — 
Care of. — To Clean Pen Blades. — To Sharpen. — To Test. 

22. Compasses 23 

Purpose. — Names of Parts. — Materials of. — Design of. — The Socket- 
joint and Head-joint Design. — The Needle Point. — The Extension 
Bar. — To Prepare and Use the Compass. 

23. Dividers 26 

Purpose. — Design and Materials. — Use of. 

24. Bow Dividers 27 

Purpose and Advantage. 

25. Bow Pencils 27 

Purpose and Advantage. — Ordinary Design of. — Materials of. — Special 
Design of. — To Prepare the Bow Pencil. — To Test. 

26. Bow Pens 28 

Purpose. — Requirements, Care and Use of. 

27. Scales 29 

Purpose. — Engineer's Scale. — Architect's Scale. — Materials and 
Design. — Scale of Triangular Cross Section. — Proper Use. — To Test. 

28. Protractors 31 

Purpose. — Materials and Design. — Use of. 



CONTENTS • xi 

Sec. Page 

29. Machinist's Calipers, Dividers, and Steel Rule 32 

Use of. — Materials and Design. — Outside Calipers. — Inside Calipers. 
— Proper Use of Calipers. — Design and Use of Dividers. — Microme- 
ters and Extremely Accurate Measurements. 

30. Blotter, Penwiper, and Instrument Rag 33 

Use of Blotter. — Use of Linen Pen Rag. — Use of Instrument Rag. 



CHAPTER II. 

Letters, Numerals, and Lettering. 

31. Introductory 34 

Importance of Good Lettering. — Simple Style of Lettering. — Gothic 
Alphabet. — Ability to Letter. 

32. The Study of Lettering 34 

Not a Purely Mechanical Process. — Outline and Characteristics of 
Letters. — Grouping of Letters. — Sense of Proportion. — Practice and 
Patience. — Critical Study of Lettering. 

33. Slope of Letters 36 

Advantages of the Inchned Alphabet. — Slope Used in this Work, and 
how Obtained. 

34. General Description of Model Letters 37 

The Stem, Definition of. — Top, Bottom, and Side Guide Lines. — Center 
Lines in lettering. — Dimensions on Model Letters. — Slope of Model 
Letters. — Direction Arrows with Numbers. — System of Strokes. 

35. Spacing 39 

Importance of Correct Spacing. — How to Judge Spacing. — Distance 
between Letters. — Element of Adjacency, Defined. — Spacing for 
Various Line Combinations in Capital Letters. — Spacing of Numerals. — 
Spacing of Capital Letters in Combination with Small Letters and of 
Small Letters. — Spacing between Words. — Spacing between Sentences. 

— Spacing Allowed for Punctuation Marks. 

36. Systematic Method of Lettering 44 

37. The Size and the Lettering of Letter Sheets 44 

Set of Free-hand Lettering Exercises. 

38. Outline and Characteristics of Capital (or Upper-case) Letters . 

Composed of Straight Lines Only 44 

Detailed Description of each of the Following Straight-line Capital 
Letters: /, L, F, E, H, T, N, M, Y, V,X,A,K,Z and W. 

39. Sheet A 48 

Exercise in Making Large-size, Straight-line Capital Letters Free-hand. 
(See Fig. 39, page 49.) 

40. The Sloping Ellipse 50 

Construction of. — Medium Slope. — Extreme Slope. 

41. Outline and Characteristics of Capital (or Upper-case) Letters. 

Composed Wholly or Partly of Curved Lines 51 

Detailed Description of Each of the following Curved-line Capital 
Letters: 0, Q, C, G, D, U, J, P, R, B, S, and the Abbreviation &. 



Xll CONTENTS 

Sec. Page 

42. Sheet B 54 

Exercise in Making Large-size, Curved-line Capital Letters Free-hand. 
(See Fig. 41, page 55.) 

43. Sheet C 56 

Exercise in Making Capital Alphabet Free-hand to a Reduced Size. (See 

Fig. 42, page 57.) 

44. Outline and Characteristics of Numerals 58 

Detailed Description of each of the Numerals: 4, 7, o, g, 6, 5, 8, 3, and 2. 

45. Sheet D 60 

Exercise in Making Numerals of Both Large and Reduced Size Free- 
hand. (See Fig. 43, page 61.) 

46. Sheet E 60 

Free-hand Exercise in Making Slant, Capital, Gothic Letters of a Size 
Suitable for Notes on Drawings. (See Fig. 44, page 62.) 

47. The Small (or Lower-case) Letters of the Inclined Gothic 

Alphabet 60 

Detailed Description of Each of the Lower-case Letters Grouped as 
Follows: 0. — a, d, g, q. — b, p. — c, e. — n, r, h, m. — «, >'. — I, i, k, 
t, f, j. — s. — V, w. — X. — 2. 

48. Sheet F 67 

Free-hand Exercise in Making the Small (or Lower-case) Letters to a 
Large and Reduced Scale. (See Fig. 45, page 68.) 

49. Designing Headings and Titles 69 

50. Sheet G 69 

Free-hand Lettering Exercise in Laying Out a Practical Title Form 

and Bill of Material. (See Fig. 47, page 70.) 

CHAPTER HI. 

Mechanical Drawing and Drafting Room Practice. 

52. Introductory 71 

The Purpose and Field of Drawing. — A Perspective Drawing. — A 
Mechanical Drawing. — Symbols and Notes on Drawings. 

53. Projection and Projected Views 73 

Orthographic Projection. — Vertical Plane of Projection. — Horizontal 
Plane of Projection. — Third Angle Projection. — Various Methods of 
"Folding" Planes of Projection. — Plan View. — Side Elevation. — 
Front Elevation. 

54. Conventional Lines 76 

Contrast between Lines. — "Weight" of a Line Defined. — Construction 

and Weight of the Visible Line, the Invisible Line, the Section Line, the 
Dimension Line, Arrow Heads, the Reference Line, and the Center 
Line.- — Symbol for Center line. — A "Finished" Line. — A Clear-cut 
Line. — A Line Free from Waves. — A Line of Unvarying Width. — 
A Line Colored to the Same Degree throughout. 

55. Sectioning and Sectional Views 79 

Purpose of a " Section." — Longitudinal Section. — Transverse Section. — 
Simple Section. — Compound Section. — Conventional Sectioning. — 
Sectioning Adjoining Pieces. — A Number to Represent a Material. — 



CONTENTS • xiii 

Sec. Page 

How to Draw and Space Section Lines. — Section Liner. — To Section 
a Large Area. — Location of the Section. — Certain Details not Sec- 
tioned. — A Quarter Section View. — A "Turned-up" Section. 

56. Number and Arrangement of Views 83 

Determining on the Views, their Number and Arrangement. — Views 
Arranged According to Third Angle Projection. — Position in which to 
Represent a Part. — Blocking Out the Sheet. 

57. Detail Drawings 85 

Purpose of a Detail Drawing. — The Number of Parts Detailed on a 
Single Sheet. — Operation Sheets. — Grouping Parts on a Sheet. — Work- 
ing Up the Views. 

58. Assembly Drawings 86 

Purpose of Assembly Drawings. — Dimensions on Assembly Drawings. 

59. Conventional Methods 87 

Various Uses of. — Lack of Uniformity in Common Conventions (see 

Fig. 65, page 88). — Conventional Method of Showing Each of the Fol- 
lowing: Sohd Shaft, Bearing, Timber Section, Hollow Shaft, Holes 
Equally Spaced Around a Circle, Broken Lines to Represent a Moving 
Arm in Extreme Positions, Broken Lines to Represent a Part in Several 
Positions, Broken Lines to Represent a Part not Completely Drawn, 
Visible V Threads, Invisible V Threads, Square Thread, National Acme 
Thread, Drilled Holes, Tapped Holes, Reference Numbers, and Cross- 
section of Steel Shapes. 

60. Drawing to Scale 90 

Explanation of. — Method of Making a Scale. — "Scales " in Common 
Use. — To "Read" a Scale. — Shrink Rule for Pattern Makers. 

61. Choice of a Scale in Drawing 93 

Best "Scale" to Use. — To Determine the Largest Scale Permissible. — 

To Find the Scale for Each of Several Parts Represented on the Same 
Sheet. 

62. Dimensioning Working Drawings 94 

Importance of Dimensions. — How to Select the Dimensions. — When 
Dimensioning is Satisfactory. — Results of Inaccurate Dimensioning. — 

To Check Dimensions. — Dimensions not to Scale. — Arrowheads, Loca- 
tion of. — Dimension Numbers, the Selection and Location of. — Abbre- 
viation for "Feet." — Symbol for Inches. — Refinement in Dimensions. 
— Dimensioning Rough Castings. — Limits in Dimensioning. — Overall 
and Sub-divided Dimensions. — Repetition of a Dimension. — Distribu- 
tion of Dimensions. — Dimensioning Similar Parts. — "Leader; " Defini- 
tion of Dimensions which Fall on a Sectioned Area; Dimensioning a 
Circle, a Cored Hole, Fillets, a Radius, a Threaded Piece, a Tapped Hole, 
Angles and Tapers. 

63. Notes on a Drawing 97 

When Necessary. — How to Compose and Lay Out. — Style of Lettering 

to Use in this Work. 

64. Indicating the Finish of Surfaces 98 

When a Surface is "Rough." — When a Siurface is "Finished." — Some 

of the Kinds of Shop Finishes. — To Indicate the Finish Desired. 



XIV CONTENTS 

Sec. Page 

65. Use of Record Forms and Titles 98 

A Complete Record of Each Drawing is Essential. — Information which 

is Necessary and which Should be Recorded. — Changes on Drawings, 
Record of. 

66. The Title-form on a Drawing 100 

Location. — No One Standard Form. — Title Form Used in this Work. 

— Style, Size and Arrangement of Lettering in Title Form. 

67. Bill of Material 100 

Where Used and Purpose of. — Form Used in this Work. — Location of. 

— Style and Size of Lettering to Use in. — Complete Explanation of the 
Bill of Material Form to be Used. — How to Call for Standard Parts. — 
Materials, Abbreviations of, in Bill of Material. 

68. Niimbering and Indicating the Size of Drawings 103 

Purpose of. — Sizes Most Generally Used. — Size of Paper for Mechan- 
ical Drawings in this Work. — Numbering of Drawings in this Work. 

69. Part Numbers on a Drawing 104 

Purpose and Location of. — Layout of Part Numbers Used in this 
Work. 

70. Recording Patterns on a Drawing 104 

Purpose and Method of Numbering Patterns. — Method of Selecting 

and Recording Pattern Numbers to be Followed in this Work. 

71. Time Keeping in Drawing 105 

Method, and Purpose of, in Practice. — System of, in this Work. 

72. Border Lines 106 

Location and Purpose of. — To Lay Out Border Lines in this Work. 

73. To Fasten the Paper or Tracing Cloth to the Board 107 

Method of Procedure. — Location of Paper and Tracing Cloth on the 
Board in this Work. 

74. To Make a Pencil Drawing 108 

General Instructions. — Systematic Procedure and Specific Instruc- 
tions in this Work. 

75. Inking Drawings no 

To Prepare the Pencil Drawing for Inking. — Inspecting the Ruling 

Pen and "Charging" it with Ink. — To Keep the Ruling Pen Working 
Satisfactorily. — General Instructions for. — Faulty and Ragged Lines. 

— Drawing Ink not to be Blotted. — Ink-bottle Holders. — Specific 
Instructions for Inking Drawings in this Work. 

76. Checking Drawings 113 

Importance of Efi&cient Checking. — General Discussion on. — Specific 
Instructions for. 

77. Tracing 114 

A Tracing Defined. — Use of a Tracing. — How to Make a Tracing. — 
Moisture Spoils Tracing Cloth. — To Clean Tracing Cloth. — Erasures 

on a Tracing. 

78. Blueprints 116 

How Made. — Changes on. 



CONTENTS XV 



SET OF MECHANICAL DRAWING EXERCISES 

Sec. Page 

79. Drawing C-ioi 116 

Detail Drawings of Lathe Spindle, Key, Fiber and Steel Washer, and 
of Special Nut (see Fig. 82, page 118). — General and Speciiic In- 
structions for Making. 

80. Tracing Drawing C-ioi 121 

General and Specific Instructions Given. 

81. Blueprint of Tracing C-ioi 121 

Purpose of Making. — Specific Instructions Given. 

82. Drawing C-102 122 

Detail Drawing of Lathe Leg. (See Fig. 85, page 123.) 

83. Drawing C-103 124 

Detail Drawing of Lathe Bed and Bracket. (See Fig. 88, page 125.) 

84. Drawing C-104 126 

Drawings of Bolts, Nuts and Screws, the Proportions of which are De- 
termined by the Student from Empirical Formulas Given in the Text. 
(See Fig. 89, page 128.) 

85. Tracing Drawing C-102 129 

86. Tracing Drawing C-103 • • ■ 129 

87. Drawing C-105 129 

Detail Mechanical Drawings made from Sketches of the following Lathe 
Parts: Tail Stock Center, Shell, Tail Stock Spindle and Tail Stock 
Spindle Clamp. 

88. Drawing C-106 130 

Assembly Drawing of Lathe Tail Stock Complete, Built Up from Draw- 
ings or Sketches of Each of the Parts Composing it. 

89. Tracing Drawing C-106 130 

90. Examination on Chapter III 130 



CHAPTER IV. 
Free-Hand Working Sketches. 

91. Introductory 131 

Value of Free-hand Sketches. — Some Uses of Free-hand Sketches. 

92. Free-hand Copies of Working Drawings 131 

Purpose of Making. 

93. Free-hand Sketches from Objects. 132 

Working Sketch Defined. — Importance of Making Sketches Correct. — 
Discrimination in Selecting and Placing Dimensions on Sketches. — 
Proportioning Sketches by the Eye and without Direct Measurements. 

— To Make an "Eye Estimate" of a Distance. 

94. Making Sketches from Memory 134 

Good Method of. 

95. The Free-hand Pencil Line 134 

The First Essential. — Specific Instructions for Making. — Drawing a 
Horizontal Free-hand Line. — Drawing a Vertical Free-hand Line. — 
Manipulating the Pencil. — To Draw a Curved Free-hand Line. 



xvi CONTENTS 

Sec. Page 

96. Free-hand Inked Line 136 

Penciled Work to First be Correct. — Specific Instructions for Drawing 

a Free-hand Inked Line. — Effects of too Much and too Little Ink on 
the Pen. — Care of Pen. 

97. Building up a Sketch 137 

Determining on the Views. — To Begin a View. — Building up and 
Completing a Sketch, General Method of. 

98. Title Form on Small Sheets 138 

Title Form on Sketch Sheets in this Work. — Style of Lettering in. 

99. Size and Ntmibering of Sketch Sheets 139 

Standard for this Work. 



SET OF FREE-HAND DRAWING EXERCISES 

100. Sheet No. i 139 

Free-hand Sketches of Lathe Shim, Small Stud, and Clamp Stud (see 

Fig. 97, page 140). — General and Specific Instructions. 
loi. Sheet No. 2 141 

Sketch of Main Casting of Lathe Headstock (see Fig. 99, page 143). 

— Specific Instructions. 

102. Sheet No. 3 142 

Sketches of Lathe Face Plate, Tail Stock Center^ and Special Nut. 
(See Fig. 104, page 145.) 

103. Sheet No. 4 144 

Sketches of Lathe Tail Stock Spindle and Shell. (See Fig. 105, page 146.) 

104. Sheet No. 5 147 

Sketches of Lathe Clamp Bolt, Hand Wheel and End Cap. (See Fig. 

109, page 148.) 

105. Sheet No. 6 147 

Sketch of Lathe Clamp Copied from Model Sketch, the Dimensions for 
which are Obtained by Direct Measurement of the Clamp being Properly 
Recorded on the Exercise Sketch. (See Fig. in, page 149.) 

106. Sheet No. 7 150 

Sketch of Lathe Tool Rest Support Slide and of Lathe Clamp for Tail 
Stock Spindle. 

These sketches are made directly from the objects themselves. 

107. Sheet No. 8 150 

Sketch of Lathe Tail Stock Screw and of Tail Stock Nut. (See Fig. 116, 
page 151.) 

108. Sheet No. 9 152 

Sketch of Main Casting of Lathe Tail Stock. (See Fig. 119, page 153.) 

109. Sheet No. 10 152 

Sketches Made Directly from Lathe Bearing Cap and Stationary Flange. 

no. Sheet No. 11 152 

Sketch of Lathe Cone Pulley Made on Plain Paper (not Cross-section 

Paper) and Directly from the Part Itself. 
III. Sheet No. 12 152 

Copying a Sketch of the Pattern and Core Box of Lathe Cone Pulley. 

(See Fig. 122, page 155.) 



CONTENTS xvii 

Sec. Page 

112. Inking Sheet No. i 154 

This exercise gives practice in making free-hand inked straight lines. 

113. Inking Sheet No. 2 154 

This exercise gives practice in making free-hand inked curved lines. 

114. Inking Sheet No. 11 154 

This exercise gives practice in inking on ordinary unruled paper. 

115. Examination on Chapter IV 154 



CHAPTER V. 

Isometric Drawing and Sketching. 

116. Introductory 156 

General Discussion of the Subject of Isometric Drawing. — Some Uses 

of Isometrics. — Advantages and Disadvantages of Isometric Drawings. 

117. Principles 157 

Statement of Important Principles on which Isometric Drawing is Based. 

118. Isometric Drawing of a Cube 157 

Method of Constructing. 

119. Definitions 158 

Definition of Isometric Axes, Isometric Origin, an Isometric Line, and 

a Non-isometric Line. — How Measurements must be Made in Iso- 
metric Drawing. 

120. Isometric Drawing of a Circle 159 

Method of Constructing. — Definition of "Construction Lines" and 
"Isometric Position." 

121. Approximate Method of Making an Isometric Drawing of a Circle. 160 

122. Isometric Drawing of a Plane Figure Composed of Straight and 

Curved Lines 160 

General Method of Constructing. 

123. Isometric Drawing of a Cube Cut by a Plane 161 

General Method of Constructing. 

124. Isometric Drawing of Wall 162 

With lAxes in Ordinary Position. — With Axes Reversed. 

125. Isometric of a Cylinder 163 

Method of Constructing. 

126. Isometric of Screw Thread 163 

Method of Showing "Conventional" Isometric Thread. 

127. Hollow Cylinder with a Quarter Section Removed 164 

Isometric Drawing of Lathe Spindle Taken as an Example. 

128. Offset Construction in Isometric Drawing 164 

129. Isometric Drawing of a Sphere 165 

General Method of Constructing. — Isometric Drawing of a Half 
Sphere; of One-eighth of a Sphere. 

130. Isometric Drawing of Lathe Cap. . . •. 166 

General Method of Constructing. 

131. Size and Niunbering of Sketch Sheets 166 

Isometric-ruled Paper. 



xviil CONTENTS 



SET OF FREE-HAND ISOMETRIC EXERCISES 

Sec. - Page 

132. Sheet 1 167 

Isometric Sketch of Tool Rest Support Shde for Lathe (see Fig. 138, 
page 168). — General and Specific Instructions. 

133. Sheet II 169 

Isometric Sketches of Lathe Key, Shim, Stud, Washer and Special Nut. 
(See Fig. 144, page 170.) 

134. Sheet III 171 

Isometric Drawing of Lathe Collar and Bearing, the drawing and all 
dimensions made by reference to the objects themselves. 

135. Sheet IV 171 

Isometric Drawing of Lathe Spindle, the drawing to be inked and made 
from observation of the object itself. 

136. Sheet V 172 

Isometric Drawing of Lathe Cap. 

137. Sheet VI 172 

Isometric Drawings of Lathe Shelf-Bracket. (See Fig. 150, page 173.) 

138. Examination on Chapter V 174 

APPENDIX A. — Drawing Room System 

140. Commercial Drawing Rooms 175 

Some System Usually Required. — Value of Systematically Carrying on 
this Work. — General Method of Procedure. — Sizes of Drawings. — 
Position of Sheet or Drawing on the Board. — Border Lines. — Number- 
ing and Lettering of Sheets and Drawings. — Title-Form and Its Loca- 
tion. — Bill of Material and Its Location. — Style of Lettering. — Con- 
nections and Abbreviations. 

INDEX 179 



ELEMENTS OF DRAWING 



CHAPTER I 

SELECTION, CARE AND USE OF DRAWING INSTRU- 
MENTS AND MATERIALS 

iT^ Introductory. The accuracy and finish of mechanical and 
geometrical drawings, as well as the speed with which the drafts- 
man works, depend to a very large extent upon the quality of 
instruments used. To secure the best results the most experienced 
draftsman requires instruments of a first-class quahty, and as 
the beginner needs all the assistance possible, he should not 
handicap himself by using instruments of an inferior grade. 
Since, in this work, a knowledge is required of what goes to 
make up instruments of a first-class quality, such knowledge 
should be gained before purchases are made, in order that the 
fullest benefits may be obtained. Thus unsatisfactory work, 
in so far as it results from the use of inferior instruments and 
suppHes, can be avoided. 

The quality of an instrument must not be judged entirely by 
its cost, but by its design, accuracy of workmanship, and the 
materials from which it is made. Some of the more costly in- 
struments are designed for extreme accuracy of adjustment, and 
are so delicate in mechanical construction that ordinary usage 
soon renders them less accurate than the cheaper but more sub- 
stantial makes. Hence, in selecting instruments it is best to 
avoid those of extremely dehcate construction, for as a rule 
instruments of simple design prove most satisfactory, especially 
for beginners. 

The best of instruments, however, will soon deteriorate and 
become unsatisfactory unless properly cared for, and the beginner 
is especially urged to cultivate the habit of seeing that his instru- 
ments are always kept in the best shape possible. 



*^ 



ELEMENTS OF DRAWING 

In the following paragraphs instruments are briefly described 
and the essential points which determine their superiority are 
noted. Before purchasing instruments read the first portion of 
each item referred to in the following paragraph and, if possible, 
consult with some experienced person as to the names of reliable 
makers of instruments and supplies. 

2. List of Instruments and Supplies Necessary for the Com- 
plete Course: 

Drawing Paper (M)*. lo sheets of drawing paper accurately 
cut to 12" X 18" and punched. (See page 4, § 3.) 

Ruled Paper (L), (S). (a) 36 sheets 8" X io|" standard 
punched (for #10 Manila cover), extra heavy weight cross-section 
paper, ruled on one side only with lines |" apart and every eighth 
line heavy. (See page 5, § 4.) (b) (S) 6 sheets '^" X '^o\" 
•standard punched extra heavy weight isometric paper ruled 
on one side only. (See page 5, § 4.) 

Tracing Cloth (M). 4 yards i8|"-wide tracing cloth of best 
quahty. (See page 6, § 6.) 

Blue-print Paper (M). \ yard 36" wide slow acting blue- 
print paper of best quality. Not to be purchased until required. 
(See page 6, § 7.) 

Drawing Boards (M). (a) i pine drawing board 19" X 26". 
(See page 7, § 8.) (b) (L), (S). i well seasoned pine board 
10" X 12" X T^" thick. 

Thumb Tacks (A), i dozen thumb tacks with small round 
heads about t^" diameter. (See page 8, § 9.) 

T-Square (M). i T-square with solid head and polished 
surfaces. Blade 26" long and preferably having edges lined with 
transparent strips. (See page 8, § 10.) 

Triangles (M). (a) i 7" transparent triangle, 45°. (See page 
10, § II.) (b) I 10" transparent triangle, 3o°-6o°. (See page 
10, § II.) 

Irregular Curve (M) i transparent irregular curve. Similar 
to K. & E. S21 or Dietzgen ^20. (See page 13, § 12.) 

* The instruments or materials marked (L) are required in lettering; 
(M) in mechanical drawing; (S) in sketching; (A) in all courses. 



DRAWING INSTRUMENTS AND MATERIALS 3 

Pencil Pointer (A), i medium-cut file (see page 14, § 13) or 
a small pad of fine sandpaper. 

Pencils (A), (a) i 4H pencil of hexagon cross section. (See 
page 14, § 14.) (b) (M) i 6H pencil of hexagon cross section. 
(See page 14, § 14.) 

Erasers (A), (a) i block of " Artgum " or a sponge rubber. 
(See page 16, § 15.) (b) Faber's (or equivalent) soft green 
"Emerald" eraser. (See page 16, § 15.) 

Erasing Shield (A), i metal or celluloid erasing shield. (See 
page 17, § 16.) 

Soapstone (A). Small piece of soapstone. (See page 18, § 17.) 

Drawing Ink (A), i bottle of black waterproof drawing ink. 
(See page 18, § 18.) 

Pens (A), (a) i each of D. Leonardt & Co.'s #506 F. and #516 
E.F., ball-pointed pens, (b) i each of Gillott ^170 and ^303; 
I Esterbrook +±182 and i Spencerian fti- (See page 18, § 19.) 

Penholders (A), (a) i penholder for ball-pointed pens. (See 
page 20, § 20.) (b) I penholder for ordinary pens. Cork-tipped 
holders preferred. 

Drawing Instruments (M). i set of drawing instruments 
of good design and quality, consisting of at least the following: 

(a) Ruling pen, 5" instrument of best quality. (See page 20, 
§ 21.) 

(b) Compass, 5", pivot- jointed instrument (see page 23, § 22) 
with handle, lengthening bar, detachable pencil and pen legs. 

(c) Dividers, 5" instrument with hair-spring adjustment. (See 
page 26, § 23.) 

(d) Bow dividers having a maximum capacity of i\" radius. 
(See page 27, § 24.) 

(e) Bow pencil having a maximum capacity of i\" radius. 
(See page 27, § 25.) 

(f) Bow pen of lest quality and having a maximum capacity 
of i\" radius. (See page 28, § 26.) 

(g) Case for set of drawing instruments. 

Scale (M), (S). i architect's 12-inch triangular boxwood 
drawing scale, graduated as follows: \", \", f", \" , f", 1", i|", 
2", 3", 4", and one " edge " graduated in inches and sixteenths of 
an inch. (See page 29, § 27.) 



4 ELEMENTS OF DRAWING 

Protractor (M). Not absolutely necessary in this course. 
(See page 31, § 28.) 

Machinist's Calipers (S). (a) i pair 6" outside spring-cali- 
pers. (See page 32, § 29.) (b) i pair 6" inside spring- 
calipers. 

Machinist's Scale (S). i 2-foot length machinist's scale. 
Not absolutely necessary in this course. (See page 32, Fig. 36.) 

Machinist's Dividers (S). i pair 6" machinist's dividers. 
Not absolutely necessary in this course. (See page 33, § 29.) 

Blotter. I ordinary 4" X 9" blotter. (See page 33, § 30.) 

Pen Wiper (A), i piece of linen cloth about 9" X 9". 
(See page 33, § 30.) 

Instrument Cleaner (A), i piece of cotton cloth about 
18" X 18" for brushing off drawings and cleaning instruments. 
(See page 33, § 30.) 

Manila Covers (L), (S). 3 standard (#10) Manila covers. 

Paper Fasteners (A), i dozen S3 brass paper fasteners with 
washers. 

Carbonate of Soda (M). Small quantity of soda for making 
changes on blue-print paper. 

'Y' 3. Drawing Paper. In selecting paper to use for any particular 
drawing, the character of the work and the purpose for which the 
drawing is to be made are the determining factors. 

In general a good drawing paper should be tough, strong, and 
of uniform thickness. It should not become brittle or discolored 
with age, and should not wrinkle nor warp during changing 
weather. The surface should stretch evenly and admit of con- 
siderable erasing without injury. 

t For inked drawings, the surface of the paper selected should 
neither repel nor absorb Hquids. If the paper repels ink the 
lines will be irregular and uneven. An illustration of this is 
seen if an inked line is drawn on oily paper. If the paper 
absorbs ink, the line will spread and resemble a line drawn upon 
blotting paper. For pencil drawings, paper with an unpolished 
surface should be selected, since it will take a pencil mark more 
readily than paper with a polished surface and does not require 
the same care in making erasures. There is little difiference in 



DRAWING INSTRUMENTS AND MATERIALS 5 

the two sides of good drawing paper, but the side from which the 
"water-mark" reads correctly is meant to be the working side. 

A cheap grade of Manila paper will do for such pencil work as 
shop drawings, prehminary sketches, drawings to be traced, and 
in general all drawings not requiring extreme accuracy nor 
intended to be of permanent value. A better grade of paper 
should be used for work of a more exacting character. 

Whatman paper is used extensively for making permanent ink 
drawings. There are two grades suitable for this purpose; 
namely, hot pressed and cold pressed. The hot pressed 
(marked H.P.) has a smooth surface, and is used principally for 
fine-Hne drawings. The cold pressed (marked N. to signify not 
hot pressed, and sometimes marked C.P.) is used extensively for 
tinted and water-color work. 



r 4. Ruled Paper. In the study of free-hand lettering and in 
sketching, the beginner can save much time and secure greater 
accuracy by using specially ruled paper, the advantage being 
that proportion can be obtained without the aid of measuring 
instruments. 

Fig. I (a) shows cross-section ruling, the small squares being 
one-eighth inch, 
and every eighth 
line is extra 
heavyso that the 
one-inch squares 
stand out promi- 
nently. This 
paper is used in 
ordinary sketch- 
ing, etc. 

Fig 




(b) Isometric Ruling. 



(a) Cross-Section Ruling. 

Fig. I. — Ruled Paper. 

I (b) shows isometric ruling, which is used in making 
isometric perspective sketches. 

Care must be exercised in cleaning drawings made on cross- 
section paper, as cleaning with either the eraser or the "artgum" 
tends to dim the section lines and thus spoil the work. 

Make all Hnes light weight and with a medium soft pencil 
then retrace the Knes that are to be permanent and clean the 
drawing. This method insures the least amount of erasing. 



6 ELEMENTS OF DRAWING 

5. Tracing Paper. Tracing paper is a thin, transparent paper 
which is used for making tracings that are usually (but not 
always) to be of a temporary character. It is cheaper than 
tracing cloth, but inferior to it in permanency. Blue prints 
made from drawings on tracing paper require longer exposure 
and are not so distinct as those made from drawings on tracing 
cloth. 

6. Tracing Cloth. Tracing cloth is a specially prepared hnen, 
having one side finished with a smooth glazed surface and the 
other dull finished. Either side will take ink and there is a differ- 
ence of opinion among draftsmen as to which is the better side to 
work on. The glazed side is better for lettering and free-hand 
work in general, as there is less tendency to catch the pen point 
and cause blotting; also, since the glazed coating holds the ink 
and keeps it from soaking into the fibers of the cloth, it is easier 
to erase ink from this side. The chief disadvantages are that 
the glazed side does not take the ink quite so readily; also 
the tracing tends to curl up when the inking has been done on 
the glazed side. The dull side takes ink more easily, and if any 
lines are to be penciled directly on the cloth (as in making alter- 
ations, additions, etc.) the rough surface of the dull side takes 
these hnes more readily. For the same reason the dirt collects 
from the triangles and T-square. The glazed side is recom- 
mended for beginners and with experience the draftsman will 
determine his preference. 

In cutting the tracing cloth (called for in the fist of neces- 
sary suppHes) into sheets for use, see that each sheet is large 
enough to permit of cutting off the margin containing the thumb 
tack holes when the tracing is finally trimmed to the standard 
size (12" X 18") • Also, in cutting the cloth, care must be exer- 
cised to avoid breaking its surface, as creases and broken places 
render the cloth unfit for use. 

Only a good quality tracing cloth should be used. 

7. Blue-print Paper is a specially prepared paper, having one 
side coated with chemicals which are sensitive to light and which 
will turn a rich permanent blue after the paper has been exposed 



DRAWING INSTRUMENTS AND MATERIALS 






to the light and washed in clean water. Blue-print paper is 
seldom prepared in the drafting room since it can be bought 
cheaper in the open market. A formula for preparing blue-print 
paper is as f oUows : 

2| ounces Red Prussiate of Potassium in i pint of water. 

4 ounces Citrate of Iron and Ammonia in i pint of water. 

Dissolve thoroughly and filter; then mix and apply evenly on 
one side of the paper with a sponge or a broad, thin brush. The 
paper must be prepared in a dark place and must be stored in 
a dark dry place. 

•^ 8. . Drawing Boards. A drawing board should be made of a 
V light weight material which is not greatly affected by changes of 
weather, and which will take the thumb tacks easily and hold 
them securely. Also, the board should be designed to allow for, 
or resist as far as possible, any change in shape due to warping or 
handling. The best material for a drawing board is thoroughly 
seasoned, soft, white pine, free from knots or pitch. The best 
design depends largely on the size of the board. 

The board recommended for use in this work, both as to 
design and size, is shown in Fig. 2. This board consists of a 




Ordinary Drawing Board. 



central portion or " body," in which part the grain should run 
lengthwise, and " end strips " so placed that the grain runs at 
right angles to that of the body. 

The body and end strips are united by a glued tongue and 
grooved joint. In some instances the end strips are made of 
hard wood in order to better resist warping or being nicked in 
handling. This construction will resist excessive warping in 



8 ELEMENTS OF DRAWING 

small boards, but the larger sizes are usually made with a pair 
of hard-wood ledges screwed or dovetailed to the back, and in 
addition there is a series of saw grooves cut lengthwise on the 
back of the body of the board. 

The drawing board should be covered with a light coat of 
shellac to protect it from moisture and to keep it clean. 

The top surface is termed the working face (see Fig. 2, 
page 7), and should be a perfectly smooth plane. The left-hand 
edge is termed the working edge, because it acts as a guide for 
the T-square head. The working edge should be perfectly 
straight and smooth and free from nicks. The straightness of 
the working edge should be tested occasionally by placing a 
standard straightedge, or the edge of a T-square blade which is 
known to be perfectly straight, along it to see if the two coin- 
cide throughout. 

9. Thumb Tacks. For all ordinary work the drawing paper 
or tracing cloth is secured to the drawing board with thumb 

tacks. These tacks are inexpensive and only the 
best should be used. A good form is shown in 

Fig. 3- 

The tack should be small and the outer edge 

of the " head " should be thin so as not to inter- 

' if*'*'* *'' f^^^ with the free use of the T-square and triangles; 

If as a rule, small thumb tacks are preferable, say yg" 

Fig. 3.— Ordinary diameter. 

Thumb Tack. q^^ \.2S^^ should be used at each corner of the 
sheet, and if the drawing or tracing is large, enough thumb tacks 
should be placed along the edges to hold the paper or cloth 
securely on the drawing board. Tracing especially can be done 
much more rapidly if the cloth fits closely to the paper drawing. 

10. T-Squares. The T-square derives its name from its resem- 
blance to the letter T and from its use in " squaring " the paper 
on the drawing board. It is intended primarily to serve as a 
ruling edge in drawing horizontal lines (that is, lines perpendicular 
to the working edge of the drawing board), and to provide an 
edge for guiding the triangles in drawing vertical or inchned hnes. 




DRAWING INSTRXJMENTS AND MATERIALS 9 

In its simplest form (see Fig. 4) the T-square consists of a thin 
*' blade" securely fastened at right angles to a thicker and shorter 
piece termed the "head." 




Fig. 4. — Ordinary T-Square. 

In a more elaborate design the head is pivoted so that it can 
be adjusted and fastened at any angle with the blade. This 
arrangement enables the draftsman to use the working edge of 
the drawing board to guide the T-square in drawing a series of 
parallel hues that are not perpendicular to that edge. While 
this "swivel head" is sometimes an advantage, it is not neces- 
sary for ordinary use and the design shown in Fig. 4 is 
recommended. 

T-squares are made of wood, rubber and metal, the most satis- 
factory being made of wood and having the edges of the blade 
lined with a narrow strip of transparent amber or celluloid. The 
blade should be as long as the drawing board, and it is desirable 
to have the blade and the head exactly at right angles in order 
that the Hnes drawn with the T-square will be at right angles 
to the working edge of the drawing board. This, however, 
is not absolutely necessary, for if the working edge is straight 
and the T-square is properly used, the lines are always drawn 
with reference to the working edge of the board, and are there- 
fore parallel, and the drawing will be accurate. 

The T-square should be polished or given a coat of shellac in 
order that dirt may not adhere to its surface; for unless the 
blade is perfectly clean it will soon soil the drawing in rubbing 
over it. 

To test the straightness of the working edge, use a pencil 
having hard lead sharpened to a fine chisel edge (see page 15, § 14) ; 
hold it against the working edge of the T-square and draw a Une 
the full length of the blade. Turn the blade over (i.e., revolve 
about the lines just drawn) so as to bring the opposite side 
against the paper, and if the working edge does not coincide with 



lO ELEMENTS OF DRAWING 

the line throughout its entire length, this edge is not "true." 
The inside edge of the T-square head may be tested by apply- 
ing any standard straightedge to it. 

Care must be taken that the blade is not loosened, and that 
the working edges are perfectly straight and free from nicks. 
The T-square must not be used to hammer thumb tacks into 
place, and the top or working edge of the blade must never be 
used to guide the knife in cutting paper or tracing cloth, as the 
smallest nick will disfigure all lines drawn by the aid of that 
portion of the blade. The lower edge of the T-square, however, 
may be used as a straightedge for trimming drawings or cutting 
paper. 

To use the T-square, hold it near the center of the head with 
the left hand, and, with a steady but unstrained grip, slide the 
inner face of the head along the working edge of the drawing 
board until the top edge of the blade is in the proper position for 
drawing the line or guiding the triangle. The lower edge of 
the blade should never be used in this way, as it may not be 
parallel to the working edge, and as a result all lines drawn 
would not be parallel. 

The habit should be cultivated of "feeling" that the T-square 
is in perfect contact before drawing a line. That is, the head 
should set firmly against the working edge of the drawing board 
and the blade should lie perfectly flat on the drawing. 

II. Triangles. Triangles are used as a guide for the ruling pen 
or the pencil in drawing lines at an angle to the T-square blade. 
All the angles of a triangle must be true and its edges straight 
and free from nicks. The material of which it is made should 
not warp easily, or show tendency to gather and hold dust; it 
should be light enough to be easily handled and hard enough to 
hold its edge under use. Triangles are made of wood, rubber, 
amber, celluloid, or metal. Metal triangles are accurate and 
durable, but are difficult to handle, and if dropped on a drawing 
the corners puncture the surface. Those made of wood are 
cheap and light in weight, but warp easily and are hard to 
keep clean. The triangles made of transparent amber or cellu- 
loid meet most of the requirements of a first-class instrument 



DRAWING INSTRUMENTS AND MATERIALS 



II 




(a) 45° Triangle. (b) 60° Triangle. 

Fig. 5. — Ordinary Triangles. 



and are to be preferred. An additional advantage is that, due 
to their transparency, the draftsman is enabled to see work 
already completed although it may be covered with the triangle. 
The triangles most generally used are the 45° [see Fig. 5(a)] and 
the 30°-6o°, or what is generally 
called the 60°, triangle [see Fig. 

5(b)]. 

The most desirable size of tri- 
angle to use depends largely on 
the work to be done, but the 
working edges should be long 
enough not to require working 
too close to the corners, since they become rounded with use 
and are therefore inaccurate. Accuracy in triangles is of the 
greatest importance and they should be tested when purchased 
as well as occasionally thereafter, as they may lose their 
accuracy by use. In testing the accuracy of the triangles, 
use a 6H pencil with lead sharpened to a fine chisel edge. (See 
page 15, § 14). All edges of the triangle should be first tested 
for straightness by holding them against an accurate straight- 
edge, or by the method given for testing the T-square blade (see 
page 9, § 10) and then the angles should be tested. 

To test the 90° angle for accuracy, place one of the short sides 
of the triangle against the working edge of the T-square blade 
and, with the chisel edge of the pencil held close to the triangle, 
draw a vertical line. Next turn the triangle over (i.e., revolve 
it about the line just drawn) so as to bring the opposite side 
against the paper, and, using the same edge as a guide for the 
pencil, draw a second vertical line through a point at either ex- 
tremity of the first Hne. If these two lines do not coincide 
throughout, the 90° angle is not accurate. 

To test the 45° angle for accuracy, place one of the short edges 
of the triangle against the working edge of the T-square blade, 
and, using the longest edge of the triangle as a guide for the pencil, 
draw a line. Next turn the triangle over so as to bring the 
opposite side against the paper, and revolve it until the second 
short edge is against the working edge of the T-square blade, and, 
again using the long edge of the triangle as a guide for the pencil, 



12 



ELEMENTS OF DRAWING 



draw a second line through a point at either extremity of the 
first. If the two lines do not coincide throughout, the 45° angle 
is not accurate. 

To test the 30° and 60° angles for accuracy, draw a horizontal 
line with the T-square, then place the shortest side of the tri- 
angle against the working edge of the T-square blade, and, using 
the longest edge as a guide for the pencil, draw a line to intersect 
the first line. Next turn the triangle over (i.e., revolve it 
about the line drawn) so as to bring the opposite side against the 
paper; with the same short side against the T-square, again use 
the longest edge as a guide for the pencil, and construct a triangle 
by drawing a third line to intersect the other two. If all three 
sides of the triangle drawn are not of equal length, the 30° and 60° 

angles are not accurate. 
Fig. 6 shows the 
method of using the 
triangle in connection 
with the T-square, the 
left hand manipulating 
and holding the triangle 
and the T-square. 
The draftsman should 
arrange his work so as to avoid being in a strained position, 
and the light should come from a direction that will not cause 
the T-square and triangle to cast a shadow along the edges 
being used as a guide to the pen or pencil. 




Fig. 6. — Using the Triangle in Connection with 
the T-square. 




Fig. 7. — Exact Angles that can be drawn, using Triangles and T-Square. 

Fig. 7 shows the angles that can be accurately drawn by using 

the 60° and 45° triangles and T-square. 



DRAWING INSTRUMENTS AND MATERIALS 



13 



A triangle should not be used alone in drawing lines parallel or 
at a given angle with one another, but should be guided by the 
working edge of the T-square or 
another triangle. Fig. 8 shows 
the method of drawing parallel 
lines, using one triangle as a 
guide for the other. In a sim- 
ilar manner the T-square blade 

Fig. 8. — Drawing Parallel Lines using one 
can also be used as a guide Triangle as a guide to another. . 

for the triangle to draw a series of parallel lines at any 
angle. 





Fig. 9. — Ordinary Irregular 
(French) Curves. 



12. Irregular Curves. The irregular or French curves are 

used as a guide to the pen or pencil in drawing curved lines that 

cannot be conveniently or accurately made with the compasses. 

French curves are made of the same materials as triangles, 

and the remarks on materials for triangles, therefore, apply to 

French curves (see page 10, § 11). They 

may be had of many different shapes, but 

those shown in Fig. 9 probably have the 

widest use. 

To use the French curve, locate a series 
of points on the line to be drawn, and 
carefully sketch a very light free-hand 
pencil line through them; next place the 
French curve so that its edge coincides with the longest segment 
of the free-hand hne possible, and draw this segment of the line 
by using the edge of the curve as a guide. The French curve 
is then shifted to coincide with another part of the line and the 
process repeated until the entire curve is drawn. Great care 
must be taken that the segments are well joined and that the 
entire line appears uniform and continuous. In inking such 
a curved Hne, the blades of the pen must at all times be 
tangent to the curve; otherwise the line will not be of uniform 
width. In drawing an irregular curve, especially when inking, 
it is best to first leave a slight break between segments and then, 
by a separate operation, join all segments so that the curve is 
continuous and the joined points do not show. 



14 ELEMENTS OF DRAWING 

13. Pencil Pointer. A small medium cut file, with the 
end flattened to an edge and curved (see Fig. 10), serves the 

double purpose of a tack lifter 
and pencil pointer. 

Fig. 10. -Combination PencU Sharpener Jn USing the file it should bc 

frequently tapped to remove the 
lead filings. While filing the lead or tapping the file, care 
must be taken that the filings do not fall on and smear the 
drawing. 

14. Lead Pencils. The essential quahties of a good pencil 
depend somewhat on the work to be done, but the lead should 
always be smooth and free from grit, making a clear-cut, distinct 
mark as sharp as an inked line, yet one which can be easily and 
completely erased. To meet all requirements lead is made in 
different degrees of hardness, and the grade selected will depend 
upon the kind of work to be done and the nature of the surface 
on which the drawing is made. Should the lead be too soft, the 
lines will smear, especially if the drawing is subjected to con- 
siderable handling; whereas if the lead is too hard, considerable 
pressure on the pencil point is necessary to make a visible line. 
This indents the paper, and erasing and changing of such lines 
are difficult and unsatisfactory. 

Manufacturers usually indicate the degree of hardness of the 
lead in a drawing pencil by the capital letter H, which is repeated 
as often as necessary; thus, an H pencil is the softest, then comes 
HH, then HHH, etc. 

The HHHH (called 4H) pencil is a satisfactory grade for such 
work as putting in dimensions, arrowheads, lettering, making 
sketches, and in general for free-hand work. 

The 6H pencil is a satisfactory grade for making mechanical 
drawings. 

The degree of hardness of the lead in some cases is indicated 
by a number, beginning with No. i for the softest, the numbers 
progressing as the degree of hardness increases. 

Drawing pencils of either a hexagonal or round cross section 
are made but the hexagonal pencil is to be preferred since it is 
not so liable to roll off the drawing board. 



DRAWING INSTRUMENTS AND MATERIALS 



IS 



To do satisfactory work the pencil must be kept well sharpened, 

and it is important that the beginner learn the best method of 
keeping the pencil in condition. The lead may be given either 
the round "cone point" or the flat "chisel edge." Each of these 
forms has its particular use and it is often an advantage to have 
both ends of a pencil sharpened, one end having the cone point, 
the other the chisel edge. 

The cone point is used by many draftsmen for all ordinary 
drawing, and is absolutely necessary for lettering, dimensioning, 
locating points on a drawing, and all free-hand work. 

The following method of sharpening a pencil gives a point 
that will " stand up " well under use. 

With a sharp knife, make a long, sloping cut (about seven- 
eighths inch in length), removing sufficient wood to expose a 
cylinder of lead, say, about three- 
eighths inch long. (See Fig. 
II). 

Hold the pencil at an angle 
with the surface of a file (or a 
piece of fine sandpaper), and 
draw the lead across the rough 
surface, at the same time ro- 
tating the pencil in such a way 
that the lead is worn to a cone shape of the longest slope pos- 
sible, but do not file to a sharp 
point. 

Next raise the pencil to an 
angle of about 15° and file 
the end of the lead away 
until pointed. The pencil 
point should then appear as shown in Fig. 12. 

A few strokes across the file at frequent intervals will keep 
the pencil lead in good working condition, and the long slope 
of the lead saves cutting away the wood every time the pencil 
point is sharpened. 

The disadvantage of a cone point is that it wears away very 
rapidly, and to be kept in good shape must be frequently re- 
pointed. When a number of long, continuous lines are to be 




Fig. II. — Pencil sharpened to Lead 
Cylinder only. 




Fig. 12. — Pencil Lead sharpened to Long 
Cone and to Point. 



i6 



ELEMENTS OF DRAWING 



drawn, many draftsmen prefer to use a chisel edge (see Fig. 14). 
To form a chisel edge cut away the wood as explained above. 
Next hold the pencil so it will not rotate, and at such an angle 
that by drawing it across the file the lead is worn to a bev- 
eled surface of the longest slope possible. Do not file to the 
center of the lead before turning the pencil over to file a similar 
beveled surface on the reverse side (see Fig. 13). At this stage 
the pencil should not have a sharp edge. 
Next raise the pencil to an angle of about 
15°, and by moving back and forth, at the 
same time slightly rolling, file the tip on 
one side, and then on the other side, until 
a rounded chisel edge is 
produced. (See Fig. 14.) 
The lead point must 
never be moistened, as 
lead softens from mois- 
ture, and then produces 
Fig. 13. -Pencil Lead sharp- a smcarcd line which 
ened to Rough Chisel Form ^^^j^Q^ l^g Satisfactorily 

but not to Edge. (Front -' 

and Side View.) erased. 

To put a chisel edge on the lead of the 
bow pencil or compass, fasten the lead in 
the instrument so that it projects about one '^'e- 14— Pencil Lead sharp- 

. . , 1 r-i , 1 • 1 1 ^'^^^ to Working Chisel 

quarter of an mch, and file to a chisel edge Edge. (Side and Front 
as explained above, always keeping the edge ^^^'^"^ 
of the lead perpendicular to the radius of the instrument, that 
is, tangent to the arcs to be drawn. 





15. Erasers and Erasures. Erasers are used for removing 
pencil or ink lines and for cleaning the drawing. 

The pencil eraser should be made of soft, fine-grained rubber, 
free from sand or grit, and of a texture that will not glaze, smear, 
or injure the surface of the drawing. 

The ordinary ink eraser is hard and gritty but should be flexible. 
Ink erasers often contain so much grit that they injure the surface 
of the drawing, and for this reason many draftsmen prefer a fine- 
grained, soft eraser that can be used for both pencil and ink erasing. 



DRAWING INSTRUMENTS AND MATERIALS 17 

For cleaning drawings sponge rubber, kneaded rubber, and 
"artgum" are used. The eraser should be entirely free from 
grit and soft enough to wear away rapidly, so that it will not 
mar or scratch the surface of the paper or injure the lines of the 
drawing and will constantly present a clean rubbing surface. 

In making an erasure, rub over the line with a light pressure 
until it disappears; then brush off the particles of rubber and 
paper with a clean rag so that the drawing will not become 
smeared. Beginners are liable to press too heavily when erasing, 
thinking thereby to save time. This should not be done as it 
injures the surface of the drawing. Neither should erasing be 
done so rapidly that the colored rubber heats and streaks the 
work. The surface of the drawing is liable to injury if a knife 
edge is used to scratch out lines. If the surface of the paper 
or cloth is injured in erasing, it can be improved by rubbing 
briskly over the injured area (which must be perfectly clean) 
with a smooth, hard surface (such as the bone handle of a pocket- 
knife) until the surface has become smooth. Soapstone may 
also be effectively used for this purpose. (See page 18, § 17.) 

An eraser should be perfectly clean when used, and if the 
rubbing surface does not wear off fast enough to keep clean, the 
eraser end should be rubbed upon some clean spot of the draw- 
ing board until it is free from dirt. 

Never attempt to make an erasure on a drawing which is 
not securely fastened with thumb tacks, for if held down only 
with the fingers, the drawing frequently slips and it is liable to 
be spoiled by being creased or wrinkled. 

As little erasing as possible should be done when making a 
drawing to avoid injuring the drawing surface. 

16. Erasing Shield. When erasing a line, letter, or dimension, 
care must be taken that the surrounding 
work is not injured. To prevent injury, 
thin sheets of flexible metal or transparent 
celluloid, provided with slots and holes of 
various shapes and sizes, are used to protect Fig. 15.- ordinary Erasing 
the drawing while making erasures over a Shield. 

Hmited area through these openings. Fig. 15 shows the ordinary 




1 8 ELEMENTS OF DRAWING 

form of erasing shield. It is important that the shield always 
be kept clean on both sides, otherwise when using it the drawing 
is liable to become smeared. 

17. Soapstone. Soapstone is a soft mineral (a compact, 
granular variety of talc) which gets its name because of its 
soapy feel. If the surface of paper or tracing cloth has been 
injured in erasing, it may be improved by rubbing soapstone 
over the injured portion and polishing with a clean, dry rag. 

18. Drawing Ink. Drawing ink differs from the ordinary 
ink used for writing, in that it is heavier and has no penetrating 
qualities, but merely lies upon the surface of the paper or cloth. 

The requirements of a good drawing ink are that it will flow 
freely, dry readily, and will not gum; it must contain no chemicals 
that will have an injurious effect upon the instruments or paper, 
and it must be absolutely waterproof. To be waterproof means 
that the ink will not redissolve after drying, and the lines drawn 
with it will not become blurred or defaced when exposed to 
moisture. 

Drawing ink of practically any color can be obtained, but 
only black ink should be used in making working drawings 
unless there is some special reason for using inks of other colors. 
Red ink is used occasionally for making dimension lines, center 
lines, etc., but this is considered bad practice, as the ink becomes 
faded with age, and in the case of a tracing the lines will not 
be sufficiently opaque to print well. 

The use of bottled India ink is almost universal in modern 
drafting-room practice. Drawing ink gradually thickens due 
to evaporation and the bottle should therefore be kept tightly 
closed when not in use. When the drawing ink becomes too 
thick it may be thinned by adding a few drops of diluted 
ammonia or distilled water. 

If the stopper and filler are left out of the bottle, the ink will 
dry upon them, and the solid particles of dry ink will form 
small clots, which may be transferred to the pen and obstruct 
the free flow of the ink. 

19. Ordinary pens. Four styles of pens are found in drafting 
rooms: (i) the ordinary writing pen -mth. fine point; (2) the or- 



DRAWING INSTRUMENTS AND MATERIALS 19 

dinary writing pen with stub point; (3) the hall-pointed pen; 
and (4) the crow-quill pen. The style of pen selected is largely- 
determined by the width of the lines to be made. An expert 
draftsman can use the ordinary fine-pointed writing pen for 
almost all classes of work, but the beginner will find it easier 
to make relatively heavy lines with the stub-pointed or the ball- 
pointed pen. 

The ball-pointed pen is designed to glide smoothly in any 
direction and at the same time make a line of uniform width. 
It has little tendency to catch in the surface and splash the ink, 
and therefore permits of greater freedom in any direction and 
order of strokes when lettering or making free-hand lines. 

The crow-quill pen is not satisfactory for ordinary work, 
especially for tracing, as the tendency is to make the lines so fine 
that they will not reproduce in printing. 

A good general rule to follow in selecting a pen is that, when 
perfectly clean and carrying a reasonable quantity of ink, it will 
make a line of the desired width without requiring a pressure 
great enough to open the point. 

The pen selected is largely a matter of individual preference, 
and experience will soon dictate the best pen for the different 
kinds of work. Until the beginner has had sufficient experience 
to make an intelligent selection, only those pens called for in the 
list of supplies should be used. (See page 3, § 2.) 

A new pen often gives trouble from two causes: (i) the flow 
of the ink may not be free and uniform; (2) the point may be 
stiff and catch in or scratch the surface. The coating of oil 
which has been put on the pen by the makers, to prevent rust- 
ing, is usually the cause of the ink's not flowing freely on a new 
pen. This oil can be removed by moistening and thoroughly 
wiping the pen several times, or by rubbing the pen with finely 
pulverized crayon or tracing-cloth powder. Dried ink on the 
pen point will also give trouble and for this reason the pen 
should be thoroughly cleaned each time before dipping for a new 
supply of ink. 

If the pen is stiff it may be improved by slightly drawing the 
temper. This is done by holding a lighted match to the point, 
care being taken not to overheat it. 



20 



ELEMENTS OF DRAWING 



If the pen point catches in or scratches the drawing it should 
be rounded by a few light strokes on an oilstone or on a piece 
of very fine emery cloth. 

A new pen always requires " breaking in " and for this reason 
an experienced draftsman will take as much care in preserving 
his pen as if it were one of his more costly instruments. Before 
putting the pen away always clean it thoroughly with a rag free 
from lint. Common writing ink should not be used on a pen 
intended for drawing, as it corrodes the pen and renders it unfit 
for further use with drawing ink. 



20. Penholders. The penholder should hold the pen securely 
and firmly and should be of such a size and shape that the hand 
will not be cramped. Holders of small diameter are 
therefore unsatisfactory. The cork-tipped holder 
has the double advantage of being easy on the fingers 
and of absorbing moisture. 

21. Ruling Pens. The simplest, and probably the 
best, form of ruling pen consists of two "blades" 
made of a single piece of metal and fastened to a 
handle, as shown in Fig. i6. In order to hold a fine 
edge the blades must be made of the best tempered 
steel. The inner blade (into which the screw is 
tapped) should be almost straight. The outer blade 
should be slightly curved, so that, when the points 
are together, there exists a cavity of sufficient capacity 
to hold enough ink to do a reasonable amount of 
work and not evaporate too rapidly as it would if the 
film of ink were very thin. The "nibs" must be 

POINT . ... 

even m length and terminate m a slightly rounded 

dinary Ruling poiut; they must havc a moderately sharp edge, and 

^®°" must be broad enough not to wear away too rapidly. 

The handle should not be made of a material which breaks easily. 

The adjusting screws of all instruments should have an 

occasional application of light oil to prevent rusting. 

To adjust the pen, hold it toward the light, or over a piece of 
white paper, so that the space between the nibs can be seen ; then 



DRAWING INSTRUMENTS AND MATERIALS 



21 




Fig. 17. — Charging Ruling Pen with 
Ink. 



turn the thumb-screw until this distance is the width of the line 

to be drawn. To fill the pen (see Fig. 17), use the filler that is 

attached to the stopper of the 

ink bottle, and let the ink flow 

between the nibs until it is nearly 

one-quarter of an inch from the 

points. 

While filling the pen never 
hold it over the drawing as ink is often dropped during the 
process. After the pen has been filled, see if any ink has gotten 
on the outside of the nibs, and if so, wipe them off with a clean 
rag (seepage 33, §30). 

To use the pen (see Fig. 18), hold it with the thumb and the 
first two fingers, so that the thumb-screw is away from the body, 

and the pen perpendicular to the surface 
of the drawing. The third and fourth 
fingers should rest lightly on the triangle 
or T-square blade, to steady the hand 
and control the pressure of the pen 
against the drawing. This pressure and 
the speed at which the pen is moved 
along the ruling edge must not vary, 
or the line will not he uniform through- 
out its length. The pen may be inclined slightly in the direc- 
tion in which the line is being drawn, so that, in moving, the 
point is pulled after the body of the pen; but ^ 
under no condition should it be inclined in the 
opposite direction, making it necessary to push 
the point in advance of the body of the pen. 
Move the pen from left to right in drawing 
lines, which are horizontal or nearly so, from 
bottom to top in drawing lines which are vertical 
or nearly so, and in either direction (depend- 
ing upon the angle) in drawing inclined lines 
(see Fig. 19). Always hold the pen so that a Fig. 19.- Direction in 

\ 07/ ^ J ^ r- ^ which to draw Ruled 

line of the least width is drawn for a given set- Lines. 

ting of the nibs. In no case is the ruling pen to be used in 

vdoking free-hand lines as this is liable to injure the nibs. 




Fig. 18. — Using the Ruling Pen. 




^C 



22 



ELEMENTS OF DRAWING 




The blades of all pens must be kept absolutely clean, both 
inside and out, if good results are to be obtained. More unsatis- 
factory work results from the neglect of this precaution than 
from any other. No pen can be expected to make a good line 
when the blades are incrusted with dried ink. Ink corrodes the 
metal points, as shown by the magnified view in Fig. 20, and the 

pen is finally rendered unfit for use. 

As soon as the ink in the pen begins to thicken, pass 

a strip of paper or cloth between the blades, and refill 

the pen; but never refill without first cleaning the inner 

surface of the blades. 
Fig. 20. — To clean the inner surface of the blades, fold a piece 
Blade cor- of uuglazcd paper, or the rag penwiper, until thick 
^gg^.^"^^"enough to spring the nibs slightly when passed between 

them. Draw the paper or cloth between the blades, 
from the screw to the tip, several times, or until it shows no 
ink, even after being moistened. (See Fig. 75, page no.) 
Besides frequently cleaning the pen while in use, the blades 
should be opened wide and given a thorough cleaning with the 
instrument wiper before it is put away. 

The points of the pen will wekr dull after it has been used for 
some time, and in order to again make a clear-cut line they 
must be resharpened. 

To sharpen the ruling pen, first clean thoroughly and then 
close the blades until they nearly touch. This can be judged by 
properly holding the pen to the light or over a piece of white 
paper. Next, keeping the pen per- 
pendicular to the surface of a flat, 
close-grained oilstone, move back 
and forth until the nibs are " square " 
and of equal length. The nibs are 
then rounded to a radius of one 
thirty-second of an inch by ruling a 
line on the oilstone and continually 
changing the inclination of the pen, 
as shown in Fig. 21. This process dulls the edge of the points 
and they must then be sharpened by slightly opening the blades 
and rubbing the outer surface of the nibs on the oilstone. Care 




Fig. 21. — Rounding the Nibs of 
the Pen. 



DRAWING INSTRUMENTS AND MATERIALS 



23 



must be taken that the rounded shape of the end is not altered; 
also a " wire edge " must not be produced, as this will cut the 
surface of the paper or tracing cloth. 

To test the condition of the pen, clean it thoroughly and draw 
a light and heavy inked line; if 
both are not clear-cut and even, 
the pen requires attention. 



22. Compasses. The compass 
is used in drawing circles and 
arcs of circles. A complete com- 
pass outfit (see Fig. 2 2) consists of 
five parts: (i) the ''head piece"; 
(2) the "needle point"; (3) the 
"pencil leg"; (4) the "pen leg"; 
(5) the "extension bar." 

The instrument may be made 
of iron, brass, steel, aluminum, 
or German silver, the best being 
made of rolled (not cast) German 
silver. It is difficult to deter- 
mine the quality of German sil- 
ver by inspection, but the cast 
material can usually be detected 
by its high glossy finish. 

The de- 





SOeKET^Ol 



X. SCEEWO 10,9 

SLEEDLE 
POXUr 1 1 U l-EAD g 



Fig. 22. — Compass Outfit Complete. 



sign of the 

compass 

should be 

such that the "head" and "knee joints" 

allow free movement of the parts and at 

the same time give proper rigidity. They 

should be so designed as to exclude dirt 

and moisture and should fit accurately. 

Fig. 23.-Head- Joint Design, ^j^^ ^^^^^^ j^j^^^g gj^^^j^ g^ ^^le shank 

accurately, hold the leg in proper alignment, and have a clamping 
device that will hold the interchangeable parts rigid. Fig. 23 
shows the details of a good design for the head joint.. 



24 



ELEMENTS OF DRAWING 



(a) Superior design. 




The legs are alike at this joint, and two pivoted screws are 
inserted in the yoke of the handle to hold the legs in position; 
small set screws prevent the pivoted screws from turning in the 
yoke. All contact surfaces are made circular, which insures a 
close fit for all positions of the legs, and thus excludes dirt and 
moisture. 

Several forms of socket joints are shown in Fig. 24, the 
design as shown in Fig. 24(a) being the best. The hole is made 
circular and slightly tapered. The socket 
is split, and the clamping screw is lo- 
cated on the side. 

The handle of the compass is some- 
times designed so that no matter in 
what position the upper portion of the 
legs are set, it always keeps a central 
position relative to them, and conse- 
quently is approximately perpendicular 
to the surface of the drawing when the 
instrument is being used. This is an 
advantage unless the device is so deli- 
cately constructed that the wear and tear arising from ordinary 
use soon render the entire instrument valueless. 

The needle point consists of a finely tempered steel wire which 
fits into a cylindrical socket in the lower end of the attached leg. 
It should fit the socket with a snug, sliding fit, and be clamped 
with a thumbscrew. The lower end of the needle point (which 
enters the drawing) has a shoulder to support the weight and 
pressure on the instrument when in use and thus prevents a 
hole being bored -in the drawing. 

Besides the knee joint and the shank of the pencil leg, the small, 
cylindrical, split socket that receives the lead, and the clamping 
device that holds the lead should be examined. The socket 
should be drilled accurately and of the proper size to receive 
the lead of an ordinary drawing pencil. The clamping device 
should exert a uniform pressure along the entire length of the 
socket and hold the lead secure and firm. 

The remarks on the design and care of the ruHng pen (see 
page 20, § 21) apply generally to the pen leg of the compass. 



(b) Inferior designs. 
Fig. 24. — Socket-joint Designs 



DRAWING INSTRUMENTS AND MATERIALS 



25 



The extension bar is used to increase the range of the com- 
pass, by making it possible to draw circles of a larger diameter 
than can be drawn with the compass proper. Its design is 
determined by the design of the socket joint of the compass. 

The joints of instruments should have an occasional applica- 
tion of light oil to prevent rusting and insure easy working. 

To prepare the compass for use, insert the pen leg in the socket 
as far as it will go, and then clamp it securely in position. Ad- 
just the needle point so that the point of the pen and the shoulder 
of the needle are even when the compass is completely closed. 
The needle point is now adjusted for either pen or pencil and 
should not be changed. As the lead in the pencil wears away, 
making readjustment necessary, the position of the lead should 
be changed and not the needle point. The lead is usually 
sharpened to a chisel edge (see page 15, § 14) which must be 
tangent to the arc it draws. It is adjusted by clamping the pencil 
leg in the instrument and ad just- 
ing the lead until the end is even 
with the needle point when the 
compass is completely closed. 

To draw a circle, bend both 
legs at the knee joints an equal 
amount, and enough to bring the 
marking point and the needle 
point each perpendicular to the „. tt ■ .t, /- 

'^ IT JT Fig. 25. — Using the Compass. 

surface of the drawing when 

the instrument is being used. This adjustment (see Fig. 25) 

places the needle point in 
such a position that it will 
make the smallest hole pos- 
sible in the drawing and 
insures both nibs of the pen 
bearing evenly on the paper. 
The proper opening be- 
tween the points (the ra- 
dius) may be taken from the 

Fig. 26. — Setting or Reading the Instrument. measuring SCale, aS shoWU 

in Fig. 26, or the extremities of the radius may be marked from 





26 



ELEMENTS OF DRAWING 



the scale directly on the drawing in their proper position and the 
compass set to them, the latter method being preferable as there 
is less chance of injury to the scale division marks. 

To use the compass hold the handle of the instrument lightly 
between the thumb and the first and second fingers ; guide the 
needle point to the center of the circle by sliding it on a finger 
of the left hand; hold the compass so that both the marking 
and the needle points are perpendicular to the surface of the 
drawing and remain so while making the circle. Place the needle 
point at the center, and the marking point at the bottom of the 
circle, and with a slight pressure against the drawing 
rotate the compass right handed, that is, in the same 
direction as the hands of a clock move (never the 
reverse) by rolling the handle between the thumb 
and first finger. 

All inked arcs and circles should be made by one 
continuous revolution, and where any portion of a 
line is so thin or ragged as to require retracing, the 
entire line should be retraced. 

The compass should be manipulated with one 
hand, unless the lengthening bar is used, then the 
needle point should be steadied with one hand, and 
the marking point rotated with the other. 



23. Dividers. The dividers (see Fig. 27) are used 
to transfer distances from one point to another, or 
to divide lines or circles into equal parts, but they 
should not be used to transfer measurements from 
the scale to the drawing when this process injures the 
division marks on the scale. See page 25, Fig. 26. 
Neither should the dividers be used where it is 
possible to lay off or measure distances accurately 
Or- with the drawing scale. See page 30, Fig. 32. 

In design the dividers are similar to the compass, 
and the main points considered with reference to the compass 
apply to the dividers (see page 23 , § 2 2) . The legs of the dividers 
must be of the same length, and the steel points should be conical 
and sharp. One of the legs should be provided with a hair- 



Fig. 27. 

dinary Dividers 



DRAWING INSTRUMENTS AND MATERIALS 



27 



spring, controlled by a thumbscrew, to facilitate delicate 
adjustment. 

To divide, or step off, a line or circle, manipulate the dividers 
with one hand, and, with first one divider point and then the 
other as a center, rotate the dividers alter- 
nately to the right, then to the left as if 
describing a series of semicircles. 

To insure accuracy and neatness, the 
dividers should never be lifted entirely off 
the paper while being used, and the points 
should merely rest on the drawing and not 
puncture it. 




T, SCREW 



Fig. 28. — Ordinary Bow 
Dividers. 



24. Bow Dividers. The bow dividers 
(see Fig. 28) are used in the same manner 
and for the same purpose as the large 
dividers (see page 26, § 23). 

The bow dividers when once set main- 
tain a fixed distance or radius and there- 
fore in "stepping off" distances they should be used in preference 

to the large dividers. 

The points to be observed in select- 
ing, using, and caring for the other bow 
instruments apply largely to the bow 
dividers (see § 25, this page). 




25. Bow Pencils. This instrument 
is practically a pencil compass of small 
radius. In making small arcs or circles 
it has the advantage of being easier to 
handle than the large compass, also in 
drawing several arcs or circles of the 
same diameter (as for example in repre- 
senting bolt holes, boiler tubes, fillets, 
corners, etc.) there is less liability that 
the distance between the points (that is the radius) will be 
changed in the handling of the instrument. The ordinary form 
of Bow Pencil is shown in Fig. 29(a). 



(a) Ordinary Design. 
Fig. 29. — Bow Pencils. 



28 



ELEMENTS OF DRAWING 



The legs of the bow pencil should be made of one continuous 
piece of steel, finished and tempered; the handle should be made 
of metal, as ivory and bone handles break too easily; the needle 
point should be made of tempered steel and should have a well- 
formed shoulder (see page 24, § 22). The spring should be 
strong and stiff; the threaded parts cut smooth and true, and 
the adjusting screw capable of bringing the needle and lead 
points together. 

Another design of spring instruments [see Fig. 29(b)] has a 
central thumbscrew and a right and left thread working in swivel 
sockets. The advantage claimed for this design 
is that the instrument can be set in one half the 
time required to set the instrument shown in 
Fig. 2 9 (a) . The disadvantages are that the radius 
is much more liable to change in handling, and 
the swivel sockets are necessarily delicate, easily 
injured and wear rapidly. 

The lead used is the same as for the compass, 
and it is sharpened and adjusted in the same 
manner (see page 25, § 22), except for extremely 
small circles, when the lead should be sharpened 
to a conical point (see page 15, § 14), 

To set the bow pencil shown in Fig. 29(a), first 
(b) Instrument with make an approximate adjustment by compress- 

Center Adjustment. . ,-, . • ,t ,-i r i ,• .i 

Fig. 29. -Bow i^g ^^^ sprmg With the fingers and settmg the 

Pencils. thumbscrcw (this will minimize the wear on the 

adjusting screw thread); then make the final adjustment with 

the thumbscrew. The bow pencil is manipulated in the same 

manner as the compass (see page 25, § 22). 

An important test of the bow pencil is to remove the lead and 
clamp a needle point in its place (the instrument now has two 
needle points); then close the instrument, and if the two points 
meet exactly, the sockets for the lead and for the needle point 
are accurately drilled and the instrument should do satisfactory 
work; otherwise work is liable to be inaccurate. 




26. Bow Pens. The bow pen (see Fig. 30) Is used to ink the 
circles and arcs that have been penciled with the bow pencil. 



DRAWING INSTRUMENTS AND MATERIALS 



29 



ADJUSTING 
SCREW 



Its advantages over the compass are the same as those of the bow 
pencil (see page 27, § 25). The general requirements of the bow- 
pen are about the same as those for the bow pencil, and the 
remarks on the care, use, and sharpening of the ruling pen apply- 
to the bow pen (see page 20, § 21). 

The edge of the pen should be tangent to the circle, being 
drawn so that a clear cut line of uniform width is made, 
and when the instrument is closed the 
needle point should touch the pen at 
the middle of the blade end. 

27. Scales. The purpose of the scale 
is to make measurements on the draw- 
ing, and it should never be used as a 
straightedge for drawing lines. 

There are two drawing scales in gen- 
eral use: the civil engineer's, or, as it is 
usually called, the "engineer's scale," 
and the mechanical engineer's, or the 
"architect's scale." These scales differ 
in the way their inch spaces are sub- 
divided. 

The engineer's scale divides the inch into such decimal parts 
as tenths, twentieths, thirtieths, etc., and is used in such work as 
map drawing, plotting stress diagrams, measuring indicator cards, 
and in certain government work. 

The architect's scale is graduated into duodecimals (twelfths), 
to correspond to the ordinary foot rule used by the workman in 
the shop; the duodecimal is divided into halves, quarters, 
eighths, sixteenths, thirty-seconds, etc., and the scale is used for 
making all drawings of objects which are to be dimensioned in 
the ordinary foot-rule denominations. This includes practically 
all mechanical drawings. 

The best scales are made of boxwood and have beveled edges 
lined -wdth a white material resembling ivory. The division 
marks and figures are printed in black on this white background, 
and are very distinct and easy to read. There are two forms of 
scale in general use: the flat scale with beveled edges, and the 




NEEDLE pomr 
Fig. 30. — Ordinary Bow Pen. 



30 



ELEMENTS OF DRAWING 



scale of triangular cross section. The latter form is shown in 
Fig. 31 and has the advantage of combining eleven distinct 
scale divisions on a single instrument. 

Scales are made of different lengths, but, in order to be provided 
with a full-size one-foot rule, the twelve-inch length (not cpunting 
the small spaces at each end, which are to protect the end grad- 
uations) is recommended. The numerals printed on these end 



U- 2 FT. 6i'-^ • 



^ 



S&&LE 3''=rj FT.-O" 
-1 FT. 9i^ sJ 



Fig. 31. — Ordinary Triangular Scale. 

spaces indicate the size of the scale along that bevel; thus the 
number i| on the end of the scale (shown in Fig. 31) denotes 
that this bevel is divided into spaces one and one-half inches 
long and is used to make drawings in which a length of i^ 
inches represents i foot (12") of the object represented. The 
first inch and one-half length is subdivided into twelve equal 
parts, and each of these divisions represents one-twelfth of a 
foot, or one inch. The row of figures o, i, 2, 3, etc., indicates 
the divisions that represent i ft., 2 ft., 3 ft., etc. (measuring from 
the o mark), on a scale on which i| inches equal one foot. On 
some scales the length taken to represent one foot is so small 
that inches cannot be indicated. Thus, on the -i^ scale the 
unit {i^") is divided into four parts, so that each of these sub- 
divisions represents one-fourth of one foot, or 3 inches, and the 
eye is relied upon to divide this space, representing 3 inches, 

into stUl smaller divisions. 

To use the scale in mark- 
ing off a distance, apply it to 
the drawing so that it lies fiat 
on the surface (see Fig. 32) 
and in a position to receive 

Fig. 32. - Using the Scale. ^^^ ^^^^ j^gj^^ pOSsiblc OU the 

division marks and numerals; then mark the points, defining 
the distance, with a 6H pencil sharpened to a fine cone point 
(see page 15, § 14). The scale is applied in a similar manner 
in measuring distances on a drawing. 




DRAWING INSTRUMENTS AND MATERIALS 31 

Care must be taken not to injure the sharpness of the edge of 
the scale or the division marks and numerals. 

Measurements should ordinarily be taken directly from the 
scale and not transferred from the scale to the drawing by means 
of a pair of dividers, especially if by so doing the scale divisions 
become defaced. 

Where it is necessary to set an instrument to a measurement, 
as for example the radius of an arc, the best method is to lay 
the scale on the paper and adjust the instrument along its edge, 
so as to avoid scratching or defacing the graduations on the 
scale with the points of the instrument. Where this method is 
not accurate, set the instrument as shown in Fig. 26, page 25. 

To mark off a number of consecutive measurements, such as 
2", 5", i", and I", along any straight line, keep the scale station- 
ary, and, beginning at zero, mark off in succession the distances 2", 
2" + s" = 7", 2" + 5" + I" = 8", and 2" + 5" + i" + i" = 8|". 
By this method the length of the line is equal to the sum of the 
lengths of all its parts, and the accumulation of error which is 
Kkely to result from moving the scale along the line and mak- 
ing each measurement an independent operation is avoided. 

To test the accuracy of a scale, mark off the divisions to be 
tested along a straight line. Reverse the scale, and if the sub- 
divisions do not coincide, the scale is inaccurate. 

28. Protractors. The protractor is an instrument for measur- 
ing or laying off angles. It may be made of paper, celluloid, 
brass, German silver, or steel. 
The two latter materials are the 
most satisfactory. 

Fig. 33 illustrates the style of 
protractor in most general use, 
but more elaborate designs may 
be had. 

To use this protractor, place Fig. 33. -ordinary Protractor. 

it so that the two zero marks coincide with the given line 
(produced if necessary), and the center (C) coincides with the 
vertex of the desired angle. The protractor is now in correct 
position for reading. If a line is to be drawn, making a desired 




32 



ELEMENTS OF DRAWING 



angle with the given Hne, use a cone-pointed pencil (see page 15, 
§ 14) and mark a very fine point on the drawing just at the 
outer edge of the protractor and opposite the desired angle- 
division on the scale, and a line drawn through this point and 
the point C will make the desired angle with the original line. 




29. Machinist's Calipers, Dividers, and Steel Rule. To make 
a drawing of any existing object, for example a machine, all of 
the principal dimensions must be obtained. These measure- 
ments should always be made with a two-foot rule or a ma- 
chinist's steel rule and not with the draftsman's scale. Apply 
the measuring rule as close to the part to be measured as possible. 

By use of the dividers and the 
calipers, measurements otherwise 
inaccessible can often be made. 
The best calipers and dividers 
are made of finely tempered steel 
and are provided with a spring 
nut (see Figs. 34, 35, and 38) 
which admits of rapid adjust- 
ment. 

The outside calipers (see Fig. 
34) are used to determine the 
diameters of cylinders, the thick- 
ness of flat parts, etc., and the inside calipers (see Fig. 35) are 
used to determine the diameters of holes or other inside dimen- 
sions inaccessible to the scale. 

To insure accurate results, the calipers 
must always be held against the piece 
being measured in such a manner that the 
dimension desired will be a line which is 
the shortest distance between the points of 
the calipers. For example, to find the 
diameter of a cylinder, the calipers should 
be held in a plane perpendicular to the axis 
of the cylinder, and then adjusted until 
its points will just pass freely over the cylinder. To read the 
distance between the points of outside calipers, place one of the 



Fig- 34- — Ordinary 
Outside Calipers. 



, Fig- 35- — Ordinary 
Inside Calipers. 




Fig. 36. — Reading the 
Outside Calipers. 



DRAWING INSTRUMENTS AND MATERIALS 



33 





points against the end of the rule and the other against the face, 
as shown in Fig. 36. To read the distance between the points of 
the inside caHpers, place the end of the rule and one point of 
the calipers against a flat surface, as 
shown in Fig. 37. 

The dividers (see Fig. 38) can often 
be used to determine dimensions with 
a greater degree of ac- 
curacy than is possible 
with the rule. To make 
a measurement with the 
dividers, their points 

are adjusted to fit the pig. 37. -Reading the inside 

limits of the distance calipers. 

to be measured, and the points of the dividers 

are then applied to the steel rule, as shown in 

Fig. 26, page 25. 
Measurements that must be made extremely 
Fig 38 —Ordinary ^ccurate cauuot always be obtained satisfactorily 
Machinist's Dividers, with either the measuring instruments or by 
the methods of making measurements as described above. 

To measure accurately in hundredths, thousandths, etc., of 
an inch, special instruments are used, the most common of 
which is the Micrometer; a discussion of this instrument, how- 
ever, is beyond the scope of this work. 



30. Blotter, Penwiper and Instrument Rag. An ordinary 
blotter is often useful to the beginner to remove the top of a 
blot globule, but should never be used to blot the lines of the 
drawing. This dims the hnes and tends to smear the work. 

A small linen rag should be kept handy for cleaning the ink 
off the pens. 

The instrument rag should be soft and free from lint. It is 
used in keeping instruments clean, but especially in removing 
dust and dirt from the triangles and from the T-square blade. 
If these instruments are not perfectly clean, they quickly soil 
the drawing in sliding over the surface. This rag should not be 
used to clean the ink off the pens. 



CHAPTER II 
LETTERS, NUMERALS, AND LETTERING 

31. Introductory. Good lettering and dimensioning on work- 
ing drawings is of prime importance and cannot be too strongly 
urged. A drawing may be well made and correct in all its de- 
tails, but if the lettering be poorly done, the general appearance 
will be unsatisfactory and the value questionable. In most draw- 
ings the appearance is quite important, and in all it is desirable 
to secure the most pleasing effect possible. This does not mean 
that the lettering should be elaborate, or an effort made to secure 
artistic effects. There is no demand for such lettering on working 
drawings, but a style which is neat, well-appearing, easily read 
and easily made is required. The inclined Gothic alphabet, 
being free from unnecessary ornamental and superfluous features, 
fulfills all the requirements of lettering on engineering drawings 
and has been very generally adopted in practice. 

The ability to do good lettering with this style of alphabet 
depends only upon a degree of manual skill that any beginner 
can acquire by intelligent practice combined with careful obser- 
vation of the characteristics of the alphabet. 

32. The Study of Lettering. Most beginners look upon free- 
hand lettering as a diflicult but purely mechanical process. This 
is a serious mistake, and as a result progress is retarded and the 
work is uninteresting. 

The letters and numerals in the alphabets have been evolved 
through years of use, and unless the beginner studies their form 
and proportions and endeavors to reproduce them, he cannot 
hope to acquire the art of lettering. The outline and character- 
istics of each letter and numeral must he carefully studied and 
fixed in the mind. The beginner is greatly aided in learning 
the characteristics of the letters of the alphabet by so grouping 

34 



LETTERS, NUMERALS, AND LETTERING 35 

them that comparisons can be made as to their points of sim- 
ilarity and difference; for example, groups could be made up as 
follows : 

(a) Letters composed entirely of straight lines. 

(b) Letters composed wholly or partly of curved lines. 

(c) Letters of the same width. 

(d) Letters of the same height. 

(e) Letters of similar outline. 

Thus, /, L, E, and F form a group of letters all of which 
begin with a line of " standard slope " (i.e., a line which has the 
same slope as the alphabet) and have parallel branches. The 
" bar " in both the E and F is exactly midway between the top 
and bottom of the letter, and its length is the same as its dis- 
tance from the top or bottom; it is more than one-half but less 
than three-fourths as long as the upper width of the letter. The 
top width of the E equals that of the F, but the lower width of 
the E is five units while the lower width of the L is only four and 
one-half units. The fact that E is wider at the bottom than at 
the top suggests another group, composed of E, B, K, Z, and X, 
all of which are wider at the bottom than at the top. The 
reason for making these letters wider at the bottom is to give 
an appearance of stability. If these letters are made the same 
width throughout, they appear top-heavy. The /, H, N, and M 
have parallel sides which have the slope of the alphabet and 
would not appear well if made wider at the bottom. There is a 
difference in the slope of similar sides of V and W, and neither 
contains a line of standard slope. Other groups that should 
be studied are 0, Q, C, and G; P, R, and B ; U and /; a, d, g, 
and so on. This method of studying the alphabet and compar- 
ing letters will develop a fine sense of proportion and will also 
train the eye to see form properly, both of which are essential 
not only in lettering but also in sketching and drawing. 

Ultimately the draftsman does not rely upon his memory for 
spaces, widths, heights, and proportions of the letters, but this 
sense of proportion enables the eye to judge the accuracy of 
the construction, the alignment of the letters, and the proper 
spacing while the letters are being formed, and lettering free-hand 



36 ELEMENTS OF DRAWING 

is then no more difficult or tiresome than writing. Progress at 
the start will depend in a large measure upon the beginner's 
ability to criticize his own work and his willingness to correct 
all errors as soon as they are detected. 

If patience and thought are exercised from the start the be- 
ginner will soon acquire the abihty to do good lettering and it 
will then take no longer to make well-formed letters than poorly- 
made ones. 

To make a critical study of lettering, note as follows: 

{a) Whether the tops and bottoms of the letters appear to he 
in line. 

(b) If the proper spacing has been maintained between letters, 
words, sentences, and lines of lettering. 

(c) If each letter has the proper slope. 

(d) If each letter has the proper proportion of height to width. 

(e) If the different lines composing each letter are the proper 
relative length and shape. 

It will be observed that the first thing to notice is whether the 
letters appear to be in line. In lettering, mathematical measure- 
ments will not always produce satisfactory results. On account 
of the sharp angles of such letters as ^ , V, W, and the curves of 
O, C, Q, G, they appear shorter than such letters as H, N, E, 
M, when made exactly the same height, and for this reason it 
is best to make them extend very slightly beyond the guide Hne 
in order to have them appear the same height. Also it often 
happens that a deviation from the standard width of letters is 
an advantage. Thus, an L followed by an A can be made nar- 
rower than if it were followed by an N or an H, or than if it were 
at the end of a word. 

33. Slope of Letters. The vertical and the inclined alphabets 
are used in practice, but the inclined letters' are usually preferred, 
since it is more difficult to make vertical letters appear Wiformly 
regular. This is because the eye naturally compares the free- 
hand vertical lines of the letters with the mechanically made 
vertical lines of the drawing and consequently any slight im- 
perfection is noticeable. Also, to be correct and appear well, 



LETTERS, NUMERALS, AND LETTERING 37 

the vertical letters must always be exactly vertical or at right 
angles with the bottom guide line, while with the inclined letters 
the exact angle of inclination is not of great importance as long 
as uniformity of inclination is maintained, and the draftsman 
may give his letters the slope that is easiest for him to maintain. 
While, as has been said, inclined lettering is usually preferred, 
there are many instances, however, where vertical lettering, if 
well done, is preferable. 

The slope to be used in this work is 2 to i, which corresponds 
to an angle of about 63!°. To obtain a slope of two to one, lay 
off any convenient distance along a straight line and twice this 
distance on a second straight Hne erected at the right-hand 
end of and at a right angle with the first line. A third line 
joining the extreme outer ends of these two lines has the 
slope desired. The beginner should notice that the lines of the 
inclined alphabet which are drawn with a slope of two to one 
(that is, standard slope lines) correspond to the vertical lines of 
the vertical alphabet. 

34. General Description of Model Letters. The illustrations 
in § 38, page 44, and § 41, page 51, show the correct propor- 
tions of the letter, and the written matter calls attention to 
certain important points to be kept in mind when forming the 
letter. To help in this work, '' guide lines," " center lines," 
" dimension lines," and '' direction arrows " are made use of. 

The stem of a letter is any portion of the outhne which is 
straight and has the slope of the alphabet, this term being most 
commonly used in connection with the description of the small 
letters of the alphabet. 

The top and bottom guide lines limit the height of the letters 
and are an aid in keeping them in line. The side guide lines 
have the same slant as the alphabet. They limit the width of 
the letters, and aid in maintaining the proper slope. 

Center lines are used on letters having a form which can 
be divided more or less symmetrically by such lines; they also 
determine the points where certain letters are tangent to the 
guide lines. Center lines that are parallel to the top and bot- 
tom guide Hnes are called horizontal center lines; those having 



38 ELEMENTS OF DRAWING 

the same slope as the alphabet are called standard slope center 
lines, and those having a slope other than that of the alphabet 
are called sloping center lines. A letter is built around a center 
line in somewhat the same manner as a sketch would be built 
about its center Hnes. (See page 137, § 97.) 

Guide lines and center lines for lettering should he drawn con- 
tinuous or unbroken throughout their length, hut very light, as they 
are erased as soon as the lettering is completed. 

The dimensions shown on the model letters will enable the 
beginner to study the relative ratio of width to height of let- 
ters and the relative proportions of the different lines forming 
the individual letters. (See page 45, § 38.) 

The numbers appearing with the letter-dimension lines on 
the model indicate the units of space between the arrowheads. 
This unit is the length of the side of a small square of the sec- 
tion paper, and on the paper used for this work the length of 
a side is ^ inch, so that 3 would indicate the length of three 
of the small squares, or | inch; 5 would indicate five squares, 
or f inch, etc. (See page 58, § 44.) 

When the term standard slope is used in describing the model 
letters and numerals, it refers to a line of the letter having the 
same slope as the alphabet, which throughout this work is the 
slope corresponding to 2 to i or approximately to 63^°. 

Direction arrows on the model letters point in the direction the 
pencil should move in making each stroke. (See page 64.) 

The number written across the direction arrow indicates the 
order in which the strokes should be made. (See page 64.) 

This system of strokes should be closely followed by the 
beginner, as it points the way to easy and rapid lettering. 
Later on, when more familiar with the characteristics of the 
letters and when greater skill has been gained in handling the 
pencil or pen, the number of strokes may be reduced in order to 
acquire speed, but the first stroke should he the one which determines 
the spacing between the letter being formed and the preceding letter, 
the order of the strokes should follow the easiest method of secur- 
ing the desired outline, and the general direction of strokes should 
be either down (toward the body) or toward the right when 
lettering free-hand. 



LETTERS, NUMERALS, AND LETTERING 



39 



35. Spacing. It is fully as important to place letters the 
proper distance from one another as it is to form them correctly. 
Each letter in a word may be perfectly formed, but if all the 
letters have not been properly spaced the lettering will not 
appear uniform. The eye judges the space between letters as 
an area rather than a linear distance, and if separated by 
exactly equal distances, the areas outlined between adjacent 
letters will not be uniform in different combinations of straight 
and curved letters. Thus, a combination of letters with stand- 
ard slope sides falling adjacent, as MINE, would call for wide 
spacing as compared with such a combination as COG; while 
the adjacent sides of the letters of the word AT would have to 
''overhang" so that the spacing may appear uniform. Another 
extreme combination can be formed of half-open-side letters, as 
FTY. If it were possible to make these combinations fall in 
groups as illustrated, it would not be difficult to state rules 
for spacing; but with twenty-six different letters a great many 
different combinations are possible, and the problem of spacing 
cannot he covered by a single rule. Rules that will prove valuable 
to the beginner are given below but the appearance of the fin- 
ished work, in so far as spacing is concerned, will in the end 
depend upon the judgment exercised in maintaining the ap- 
pearance of equal areas between the letters. 

The distance between letters is measured in a Kne parallel to 
the top or bottom guide-line and between the side-guide-Knes 
which fall adjacent. Based on this idea the " Key to Spacing " 
(see page 43) has been compiled and the distances given below 




have been carefully found by laying out on a large scale various 
side-line combinations (see above figure) and determining a spac- 



40 ELEMENTS OF DRAWING 

ing that, in view of the area enclosed, gives the best spacing for 
such a combination. In the illustration the shaded portion rep- 
resents the " area " to be considered in determining the spacing 
which is shown between the side-guide-lines. 

By element of adjacency is meant that side-line of a letter 
which is nearest to the adjacent letter under consideration. 

(A) Spacing for various line combinations in Capital Letters 
presented in three different forms as follows: 

(I) Combinations classified by space units. 

(II) Combinations classified by side-line grouping. 

(III) Side-line combinations and corresponding spacing shown 
by chart. 

In learning to space method (I) should be the guide but as a 
further aid in certain combinations method (II) or (III) can be 
used but " spacing " has not been properly grasped until the 
judgment alone is relied on for satisfactory results. 

(I) COMBINATIONS CLASSIFIED BY SPACE UNITS 

A standard slope side followed by a standard slope side re- 
quires three and one half spaces, thus, Ns^I^Nz^E. 

A standard slope side adjacent to a curve side requires 
three spaces, thus, CzHsOzhCzE. 

A combination side followed by a standard slope or a curve 
side, also two curve sides adjacent, require two and one half 
spaces, thus, P^^R^^h^Si^^M^^.S. 

A standard slope side followed by any one of the letters, Z, 
V, W, A, X, also any one of the letters Z, V, K, W, A, X, 
followed by F or IF or by a standard slope side, require two 
spaces, thus, M2A2K2E. 

A standard slope side followed by Y or T; — a curve or combi- 
nation side followed by any one of the letters Z, F, W, A, X; — 
the letters K, X, or Z followed by a curve side; — any one of the 
letters L, Y, F, or T followed by a standard slope side require 
one and one half spaces, thus, F^^Li^E^^W. 

All other combinations require one space, thus T^O^Y'^^S, except 
T, Y and F when followed by ^, X or Z; also the L or ^ when 
followed by T or Y, which require zero spacing, thus LqAqY or 
AqT, etc. 



LETTERS, NUMERALS, AND LETTERING 41 

(II) COMBINATIONS CLASSIFIED BY SIDE-LINE 
GROUPING 

Letters with a standard slope side [H, I, M, N\ when followed 
(i) by a standard slope side [B, D, E, F, H, I, K, L, M, N, 
P, R, U] require 3I spaces. 

(2) by a curved side [C, 0, G, Q, S] require 3 spaces. 

(3) hy a 1. or a 45° side [V, W-A, X, Z] require 2 spaces. 

(4) by a half-open side [T, Y, J] require i| spaces. 

Letters with a curved side [C, O, G, Q-J, U-B, D] when followed 
(i) by a standard slope side [B, D, E, F, H, I, K, L, M, N, P, 
R, U] require 3 spaces. 

(2) by a curved side [C, 0, G, Q, S] require 2^ spaces. 

(3) hy a ± or a 45° side [V, W-A, X, Z] require i| spaces. 

(4) by a half -open side [T, Y, J] require i space. 

Letters with a combination side [R, E, P, S] when followed 
(i) by a standard slope side [B, D, E, F, H, I, K, L, M, N, 
P, R, U] or by a curved side [C, O, G, Q, S] require 2| 
spaces. 

(2) by a -L or a 45° side [V, W-A, X, Z] require i| spaces. 

(3) by a half-open side [T, Y, J] require i space. 

Letters with a -L or a 45° or a full open side [F, W-A-K, X, Z] 
when followed 
(i) by a standard slope side [B, D, E, F, H, I, K, L, M, N, P, 
R, U] require 2 spaces. 

(2) by a 1. side [V, W] require 2 spaces. 

(3) by a curved side [C, 0, G, Q, S] require i| spaces. 

(4) by a 45° side [A, X, Z] require i space. 

(5) by a half -open side [T, Y-J] require i space or o space. 

Letters with a half-open side [L-F, T, Y] when followed 

(i) by a standard slope side [B, D, E, F, H, I, K, L, M, iV, 
P, R, U] require i| spaces. 

(2) by <i ± or a curved side [V, W-C, 0, G, Q, S] require i space. 

(3) by a 4j° or a half -open side [A, X, Z-T, Y-J] require i space 
or o space. 



42 ELEMENTS OF DRAWING 

(III) SIDE-LINE COMBINATIONS AND CORRESPOND- 
ING SPACING SHOWN BY CHART 

The chart given on page 43 is used in the following manner. 
Assume as an example that the letters of the word COLLEGE are 
to be spaced. First, in the left-hand column locate the letter C, 
then move horizontally and to the right until the column contain- 
ing the capital O at the top is located, and it is seen that the side- 
line classification is curved side followed by curved side, and, reading 
directly under the and in line with the C, the spacing is 2| 
units. Similarly the combination of the letters and Z, is a 
curved side followed by standard slope line, and in a horizontal 
line with the O and directly under the L the chart shows the 
spacing as 3 units. Studying out all the combinations, the spac- 
ing is as follows: C^iOzLixLiyfiiifizE- 

(B) Spacing for Numerals. The '' standard " spacing for 
numerals is two and one half space units but in such combina- 
tions as involve the left hand side of the j, the 4 and the 7 this 
distance should be slightly reduced and in such combinations as 
involve the i or the right hand side of the 4 (measured from the 
stem) this standard spacing is slightly increased. 

(C) Spacing for Capital Letters in combination with Small 
Letters and for Small Letters. Small letters are about two thirds 
the height of capital letters and numerals of the same alphabet 
and hence small letters require a spacing of about two thirds that 
given for a similar side-line combination of the capital letters. 

(D.) Spacing between words and between sentences. Care 
must be taken to have the proper space between words and a 
greater space between sentences, otherwise the lettering is not so 
easily read, even though the individual letters are correctly 
formed and spaced. 

The spacing between words should be slightly more than 
twice the average space separating letters. 

The spacing between sentences should be about twice that 
separating words. 

Where punctuation marks are necessary extra space is allowed. 
The punctuation mark is placed nearer the word which precedes 



LETTERS, NUMERALS, AND LETTERING 



43 



Uj Q 
CQ 



S2 L^ 

0; k 

C: Uj 

I- t 

Uj Q 

-J -J 

Uj Uj 









\ 



^(0 
5 Or 



-^0 



<o 






Uj 
(0 



^ 

Q^ 



^' 



:^ 



t>- I 



I I 



I I 
I I 
' I 



1^ 



' I 



I I 
I I 

— I — ^ 



' I 









'~^ 



^ 



;;i 



fV 



\0 






I I 



fV 



i^Ai 1"^ 



fV I 
I I 









— H h 

^i 1 

p 





I I 



I I 



I I 

P 



! I 



t I 
I I 



^ 



[>^ 






I I 
I I 
I I 
II 



I I 






O 



I 

V ' 

I I 
I I 

i i: 

'; I I 

i — r-T 



^ I 
-J I 









I I 
I ' 



-4 



^: 



^ v^ 



I I 



I I I 

I I I 

' V ' ' 

1 ^ 

I I I 

-I \ — u 



I I 
^ I . 

\(\J -^ 





I I I 



(3 |(3 




^^ ^ 



I I 



-J' 



I I 



^^ 



I I 

H — \- 



I I 



Jk^^ 



-fvj 











CO , V 

c^ S^ "^ y 

> ^J H i^ 

^ S ^ W 

k ly k Q 

>*J (0 § k 



(A J 



\ 



to 

I 



^ 

^ 



^ 



k 



44 ELEMENTS OF DRAWING 

it than the one which follows. The comma and the semicolon 
each require a space between the mark and the following word 
equal to the space between words. 

36. Systematic Method of Lettering. Before starting the out- 
line of a letter, draw very lightly all guide lines and center lines 
that will be an aid in its construction. 

When forming a letter, make all lines very light at first, and, 
with the outline correct, retrace, making the lines of medium 
weight. 

All construction lines are then erased, and the correct outline, 
which will be made dim by the erasing, is again retraced and 
made clear cut and of the desired weight. In retracing, the 
strokes should always be made in the direction and order indi- 
cated by the arrows on the model letters. See § 38, this page. 

For full instructions as to how to make free-hand lines see 
page 134, § 95, also page 136, § 96. 

37. The Size and the Lettering of Letter Sheets. Exercises in 
free-hand lettering will be done on small sheets of standard letter 
size (8" X io|"), heavy weight, cross-section paper ruled on one 
side (see page 5, §4), and punched for standard 4^10 Manila 
cover. 

The order in which free-hand lettering sheets are executed will 
be indicated by capital letters, beginning with A and continuing 
as far as necessary. For full information as to the general sys- 
tem to be followed, see Appendix, p. 175. • 

SET OF FREE-HAND LETTERING EXERCISES. 

38. Outline and Characteristics of Capital (or Upper-case) 
Letters Composed of Straight Lines Only. Over half of the 
capital letters of the inclined Gothic alphabet are composed 
entirely of straight lines, and several of these straight-line letters 
are very similar. In the following paragraphs the characteristics 
of straight-line capital letters are pointed out. 

In order to fully understand the subject matter of this para- 
graph, carefully read § 34, page 37. 



LETTERS, NUMERALS, AND LETTERING 



45 




Capital I. I stroke of standard slope. The 
width of the letter is the width of the line and 
should not differ from that of all other standard 
slope lines. Do not 
dot the capital I. G.Lt 



Capital L. 2 strokes. 
#1 is standard slope ;<^ 
#2 is drawn horizontal. Note that #2 is 
shorter than the corresponding line of E. 

(See this page.) 
Capital F. 3 





strokes. ^1 is standard slope ; #2 is the 
same as #2 of E (see this page) ; ^3 starts 
from the middle of fti and is drawn 
horizontal and should never be drawn 
below the middle of the letter or be as 
long as ^2. 



Capital E. 4 strokes, fti is standard 
slope; #2 the same as ^2 oi F; (see this 
page) ; S3 the same as i^T, of F. #4 is par- 
allel to S2 but is slightly longer. tt2 is 
also longer than the corresponding line 
of the L. (See this page.) Note that 
#2 and #4 are each shorter than the 
corresponding Hnes of Z (see page 47). 

Capital H. 





3 strokes. #1 and i^2 
are each standard slope. Note that 
these two parallel lines would do for 
the N. (See page 46.) ^3 starts at 
the middle of fti, is drawn horizontal 
and should never be drawn below the 
middle of the letter. 
iifi is drawn horizontal. 



Capital T. 2 strokes. 
#2 is standard slope and is drawn from a 
point slightly to the left of the center of #1. 
Note that |fi is longer than the correspond- ^ 
ing lines of E (see this page), F (see this 
page), and Z (see page 47). 




46 



ELEMENTS OF DRAWING 





Capital N. 3 strokes, i^i and #2 are 
each standard slope, as in the H. (See 
page 45.) Stroke ^3 must meet fti and <^ 
#2 exactly at the extremes of the proper 

ends. 

Capital M. 
4 strokes. 

^i and S2 are each standard slope, 
and are drawn a distance apart 
equal to the height of the letter. 
^3 and #4 are first drawn very lightly, 
the lower segments of which are erased in the finished letter. 
The angle between S3 and ^4 must not be too acute or the letter 
will appear to be compressed, or if too large the letter will appear 
" widened." The M is not the same as the W inverted. (See 
page 47.) 

Capital Y. 3 strokes, ft i is a standard 
slope line drawn through the center of the 
letter but slightly less than the lower half is 
used in the completed letter. Strokes it2 and 
fi;3 each start from points on the top guide 
line which are equidistant from the inter- 
section of #1 (extended) and the top guide 
line and meet #1 slightly below the center. 

' .Q ^ Capital V. 2 strokes. Note especially 

that fti is vertical and #2 makes 45° with 
it; also the letter is wider at the top than 
any straight Hne letter excepting the M 
(see this page) and the W. (See page 
47.) Also i^i is not 
parallel to #2 of the 
A (see page 47), and no line has 
the standard slope. The capital and 
the small v are similar (see page 67). 
Capital X. 2 strokes. #2 has a 
slope of 2 to I and should cross fti 
at a point on the sloping center line slightly 
above the center of the letter, thus making 






LETTERS, NUMERALS, AND LETTERING 



47 




the letter wider at the bottom than at the top, otherwise it 
appears top-heavy. The capital and the small x are similar. 
See page 67. 

Capital A. 3 strokes, fti makes 45° 
with top and bottom guide lines. #2 is 
drawn from the extreme top of fti to the 
base of the right guide line and is not a 
vertical line, thus i^iis not parallel to tfi of 
the V. (See page 46.) #3 is horizontal 
and one-third the distance from the bot- 
tom to the top of the letter, and thus is 
always below the center of the letter. 
Note that no lines of this letter have the standard slope. 

Capital K. 3 strokes, fti is standard 'r 5 — "l 

slope. tt2 is drawn to meet iti at a 
point one- third the height of letter; 
i.e., below center of letter. #3 is drawn 
very lightly, the upper segment of 
which is erased in the finished letter. 
Note that the letter has a greater width 
at the bottom than at the top. 

-5 — ^ Capital Z. 3 strokes. Draw very 

lightly two sloping side guide lines. 
ifi is horizontal and starts from the 
left guide line. ^^ is parallel to fti, 
but slightly longer. Note that tfi and 
tt3 are longer than the corresponding 
lines of the E. (See page 45.) The 
capital and the small z are similar. See page 67. 
Capital W. 4 strokes. No stroke 
has the standard slope, fti and #3 
each incline slightly to the right 
and are parallel; also ^2 and U are 
parallel. Note that the letter W "f 
inverted would not be the same 
as the M. (See page 46.) The 
capital and the small w are similar. 
See page 67. 






48 ELEMENTS OF DRAWING 

39. Sheet A. The purpose of this sheet is to teacji the form 
and characteristics of the capital letters of the inclined Gothic 
alphabet, which are constructed entirely of straight lines, also 
to give practice in making these letters. 

Before starting this sheet read and be prepared for examina- 
tion on the following paragraphs: 

The Pencil Pointer, see page 14, § 13, — Lead Pencil, see page 
14, §14, — Erasers and Erasures, see page 16, §15, — The 
Free-hand Pencil Line, see page 134, §95, — Litroductory, see 
page 34, §31, — the Study of Lettering, see page 34, §32, — 
The Spacing of Letters, Words and Sentences, see page 39, § 35, 
and for information on the general system to be followed see 
page 175, Appendix A. 

Exercises on Sheet A. These exercises consist of capital 
letters of the simplest form. Before beginning the construction 
of any letter, study carefully the illustration of that letter in 
the model alphabet (see page 44, § 38) and read all descriptive 
matter relating to it. Also see § 37, page 44. 

Do not use a straightedge in doing any part of a free-hand 
exercise as this will seriously impair the value of this work. 
Lines so made are easily detected and as a result the sheet will 
not be accepted. 

Specific Instructions for Executing Sheet A . Tack down the 
sheet (see page 8, § 9), stamp in title form (see page 138, § 98) 
and the wording in the title form is next to be neatly written 
in ink. 

The title of sheet A is CAPITAL LETTERS. 

Proceed with the letters systematically, and complete the sheet 
as shown in Fig. 39, but omit arrows. Practice making a free- 
hand pencil line on scrap paper before starting sheet A. This 
practice can best be accomplished by making a free-hand copy 
of some simple drawing, such as Fig. 97 on page 140, continuing 
to practice until a " clear cut" line can be made (see page 78, 
§ 54). Also the beginner should at this time learn to sharpen 
a pencil with care (see page 15, § 14) and to use an eraser to 
the best advantage (see page 16, § 15). 



LETTERS, NUMERALS, AND LETTERING 



49 



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s 




■v 














s 






























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s, 






■v 












\ 


















































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s 
























































\ 


^ 


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\ 




















































y' 




\ 




















S 
















































< 


















S 










hi 












































Nn 


■■ 


P«v 




'^ 






> 




s 
















1 

ho 

S 
g 

•i 

•3 
1 

2 

1 
1 

1 


- 


- 





























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V 


\ 






'^ 








S 






^' 
















































^ 


[^ 










s, 




'i 












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N 












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■v 










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kn 






















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V 


















s, 










































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V 


















s 


















































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M 


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>*J 


























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k. 




































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s, 






































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' 



50 ELEMENTS OF DRAWING 

The first letter to be drawn is the capital /, and the bottom 
of this letter is to be located 23 spaces from the top edge and 
14I spaces from the first heavy vertical cross-section line on the 
left side of the sheet. 

Having satisfactorily completed the outline of all letters, 
clean the sheet (see page 17, § 15), and go over all lines, making 
them clear cut and finished. See page 78, § 54. 

Thoroughly examine the work to see that nothing has been 
omitted; correct any errors, and, after the sheet has been in- 
spected, write the Date Finished and the Total Actual Hours in 
the title form, and submit the sheet for final approval. 

40. The Sloping Ellipse. A large number of capitals, small 
letters, and numerals of the inclined Gothic alphabet have an 
outline which is partly or entirely oval. This oval approaches 
more nearly the "sloping ellipse" than any other curve, and the 
beginner should understand the construction of such a curve be- 
fore attempting to form the curved letters. The exact shape of 
any ellipse is determined by the ratio between its long and 
short axes. Fig. 40(a) shows an ellipse with its long axis 
vertical and having a ratio of width to height of 5 to 6, this ratio 
being common to many letters. This elhpse is tangent to the 
guide lines at the points i, 2, 3, 4, and is symmetrical about 
both the long axis and the short one. Therefore the diagonals 
5 to 7 and 6 to 8 are of equal length, also the four shaded areas 
outside the ellipse are equal and have the same shape. 

A "sloping ellipse" is shown in Fig. 40(b). In this con- 
struction the long axis has the slope of the alphabet (2 to i), but 
the short axis remains horizontal. When this curve is drawn in 
a parallelogram and is tangent at the extremities of the axes, 
the lines i to 3 and 2 to 4 do not divide the ellipse symmetri- 
cally. The shaded areas are therefore not of the same shape, 
but. those diametrically opposite are the reverse of each other. 
That is, in the sloping ellipse the upper left-hand quadrant of 
the curve is the same as the lower right-hand quadrant but 
reversed in relative position, and similarly the upper right-hand 
quadrant is the same as the lower left-hand quadrant but re- 
versed in relative position. The " sloping ellipse " is therefore 



LETTERS, NUMERALS, AND LETTERING 



SI 



not of the true ellipse construction but is an ellipse so modified 
that its major axis has the slope of the alphabet, and the curve 
is tangent to the Hmiting parallelogram at the extremities of the 
axes. In certain portions of the outlines of some of the capital 




(a) Vertical. 



(b) Medium Slope. 
Fig. 40. — Ellipses. 



(c) Extreme Slope. 



letters and in the case of certain small letters a much better 
shaped letter is obtained if the slope of the ellipse is made 
greater than the standard slope as shown in Fig. 40(c). Ap- 
proximately the same effect can be obtained in some of the 
capital letters by the use of circular arcs as shown in D, U, J, 
P, B, and R, pages 52 and 53. The use of the small ellipse [see 
Fig. 40(c)] in small letters is shown on pages 63, 64 and 65. 

41. Outline and Characteristics of Capital (or Upper-case) 
Letters Composed Wholly or Partly of Curved Lines. For gen- 
eral discussion of guide lines, center lines, dimension lines, 
and arrows as used in connection with lettering and numbers, 
see page 37, § 34. 

Capital O. 3 strokes. Draw 
two side-guide-lines such that 
their distance apart is equal to 
the width of the letter. Bisect 
the parallelogram by two center 
lines, as shown, and locate the 
points of tangency of the guide 
lines and ellipse. Draw in the 
sloping ellipse in the order of the strokes. For full description 
and construction of the " sloping ellipse " see page 50, § 40. 
The capital and the small are similar. See page 63. 




52 



ELEMENTS OF DRAWING 



Capital Q. 4 strokes. Three 
strokes, as for 0. (See page 51.) 
#4 is drawn very lightly from the 
left-hand point of tangency to the 
intersection of the right-hand and 
bottom guide lines. Erase about 
two-thirds of the left-hand portion 
of this line and retrace the remain- 
ing portion medium weight. 





-^ 



Capital C. 3 strokes. Proceed 
as with (see page 51), excepting 
that #2 and ^3 are shortened. The 
opening in the ellipse is slightly 
greater than one-third the height of 
letter and nearer the bottom than the 
top guide line but the letter width is the 
The capital C and the small c 




^^^ 



same as the O. 
are similar. See page 63. 

Capital G. 4 strokes, fti and S3 
are the same as for C. (See this 
page.) ^2 is longer than tf2 in C and 
extends up one-third the height of j_ 
letter. |f4 is horizontal and extends 

one-third across the letter. h ^ ^ 

Capital D. 3 strokes, fti is standard 

slope. The right-hand half of the letter 

J^is practically the same as the right 

-^- half of O. (See page 51.) The D 

is slightly narrower than the 0. 

Capital U. 2 strokes. , ^. 
Upper half of letter con- ' ^ 

I sists of standard slope 
lines, and lower half 
is practically the same as lower half co 
of 0. (See page 51.) The U is -^^ 
slightly narrower than the O. —^ 





LETTERS, NUMERALS AND LETTERING 



53 





Capital J. 3 strokes. #3 is two- 
thirds the upper portion of a standard 
slope Hne. Note that / is relatively 
narrow. The lower portion of the 
letter is part of a small modified 
sloping ellipse. See page 50, § 40, 
Fig. 40(c). 
_:^ 2 k- Capital P. 3 strokes, fii is i " ^7t\ 
standard slope. i^2 is"^! Grt. 
partly horizontal and partly small 
modified sloping ellipse. See page "^ 
51, § 40. Note that portions of 
#2 and #3 are parallel. 
Capital R. 4 strokes. #1, #2, and #3 same as c^- 

-5 — J Si, tt2, and #3 for P. (See this page.) 

#4 is drawn so as to make the R 
^p wider at the bottom than at the 
top and should be drawn in such a 
direction that it would intersect fti 
(extended) slightly above the top 
guide line. 
Capital B. 4 strokes, fti, 
#2, and part of ^3 same as ^1,^2, and 
S3 for P. (See this page.) The lower 
half (or lobe) of B is of the same form ^^ 
but slightly wider than the upper lobe 

Capital S. 3 strokes. Draw all J_ 
guide and center lines. The outline of the 
letter consists of portions of two tangent 

modified ellipses, exactly the same 
size and slope but in reversed rela- 
tive position. Si is the left half of 
upper ellipse and the right half of 
lower elhpse. S2 is drawn from the 
top point of tangency, S3 to the 
lower point of tangency. Locate 
accurately the seven points of 
tangency before "roughing in" ellipses and see that the outline 






54 



ELEMENTS OF DRAWING 




is tangent at the center of the letter but is not drawn below 
the horizontal center line at the ^. 

middle of the letter. The capital 
and the small ^ are similar. See 
page 66. 

Abbreviation &. 5 strokes. #1, 
^2, and #3 are almost the same as 
for tife numeral 8. (See page 
59.) Note especially where #4 
and ^5 begin and end. 

42. Sheet B. The purpose of this sheet is to teach the form 
and characteristics of the capital letters of the inclined Gothic 
alphabet, which are constructed wholly or partially of curved 
lines, and to give practice in making these letters. 

Having had the experience of making sheet A, again 
read paragraph 34, page 37, with reference to the Model 
letters. 

For information on the general system, to be followed see 
Appendix A, page 175. 

Exercises on Sheet B. These exercises include all capital 
letters of the inclined Gothic alphabet not given on Sheet A . 

Before attempting to form a letter, study carefully the illus- 
tration and description of that letter in the model alphabet. See 
page 51, §41. 

Specific Instructions for Executing Sheet B. Tack down the 
sheet, stamp in and fill out the title form. The wording in the 
title form is to be neatly written in ink. 

The title of Sheet B is CAPITAL LETTERS. 

Locate the letters on the sheet according to the space dimen- 
sions shown in Fig. 41 , Proceed with the lettering systematically 
(seepage 44, § 36) and complete, as shown in Fig. 41. Having 
satisfactorily completed the outline of all letters, clean the sheet 
and retrace all lines, making them clear cut and of the desired 
weight. 

Carefully examine the work to see that nothing has been 
omitted; correct any errors, and, after the sheet has been 
thoroughly inspected, write in with ink the Date Finished 



1) 



LETTERS, NUMERALS, AND LETTERING 



55 




56 ELEMENTS OF DRAWING 

and Total Actual Hours, and submit the sheet for final 
approval. 

43. Sheet C. The purpose of this sheet is to teach the beginner 
to correctly maintain all relative proportions of letters and spacing 
in lettering of the-size usually found on practical drawings. 

The first alphabet at the top of the sheet is reduced to one-half 
size; this means that dimensions given on Sheet A (page 49, 
Fig. 39) and Sheet B (page 55, Fig. 41), including the spacing, 
are reduced one-half. 

The second alphabet on Sheet C is reduced to one-third size, 
and the unit of space is one- third that given on Sheets A and B. 

The lettering in the note at the bottom of Sheet C is only one 
space high, that is, it is one-sixth size, and the spacing between 
letters, words, and sentences must be reduced accordingly. 

Specific Instructions for Executing Sheet C. Tack down the 
sheet, stamp in and fill out the title form. 

The title of Sheet C is REDUCED-SIZE LETTERING. 

Locate numbers and letters on sheet, as shown in Fig. 42 . 

When all lettering has been satisfactorily completed in pen- 
cil, clean the sheet and retrace all lines, making them the proper 
weight. 

Every possible precaution should be taken to prevent soiling 
the sheet and to avoid the necessity of making changes. As this 
sheet is to be inked, any erasing which tends to injure the sur- 
face of the drawing makes satisfactory inking very difficult. 
This sheet must be finally approved in pencil before it is 
inked in. 

Thoroughly examine the work to see that nothing has been 
omitted; correct any errors, and, after inspection and approval, 
the sheet is ready for inking. Before attempting to ink any 
work the beginner should practice inking on scrap paper. See 
page 136, § 96. Such preliminary practice accustoms the hand 
to the touch of the pen and avoids experiments on approved 
penciled sheets, which would most Hkely spoil them. 

Specific instructions for Inking Sheet C. Tack down the ap- 
proved penciled sheet on the drawing board and, before be- 
ginning to practice inking on scrap paper, read and prepare 



LETTERS, NUMERALS, AND LETTERING 



57 



^= 






:2>: 



1 



:a; 






f 



m 






1- 



-;: 



-V? 






^vi: 









=^>.- 






::;: 



Ei; 



:2: 






■i-3- 



1=E 



ii::: 



58 



ELEMENTS OF DRAWING 



for examination on the following paragraphs. Free-hand Inked 
Lines, page 136, § 96, Drawing Ink, page 18, § 18, The Ordinary 
Pen, page 18, § 19. 




44. Outline and Characteristics of Numerals. For general 
discussion of guide lines, center lines, dimension lines, and arrows 
as used in connection with letters and numbers, see page 37, 

§34. 

Four. 3 strokes, ^i is standard 
slope and its location in the limiting 
parallelogram of guide lines is very 
important, being a distance of 
three-fourths the total width of 
c>^ figure from the left guide line. S2 
-^extends downward two-thirds the 
height of the numeral. #3 is hori- 
zontal and extends entirely across 
the limiting parallelogram and gives the figure its real width, 
which is greater than any other numeral. ^ 

Seven. 2 strokes. Note especially ^ 

the width of the numeral, the curvature 
of #2, and that the end of ^2 does not 
meet the bottom guide line of the <to 
limiting parallelogram equally distant 
from the side guide lines. 

Naught. 3 '\*~~^~ 
strokes. Formed the 
same as the (see page 51) but 
slightly narrower. 

Nine. 3 

strokes. A 

small sloping ellipse 

[see Fig. 40 (c)] forms 





part of the outline. Note especially 

the angle of the center line of the small 

ellipse and that the slope of the portion of the j 

large ellipse is the slope of the numeral [see Fig. 40 (b)]. The 

form of the p is exactly the same as the 6 inverted (see page 59). 




LETTERS, NUMERALS, AND LETTERING 



59 





Six. 3 strokes. The form of the 
6 is exactly the same as the g in- 
verted (see page 58). This neces- 
sitates a change in the order of 
strokes. 

Five. 4 strokes. Lower part of 5 

is similar to lower 
ellipse of 6 (see 

this page), fti is standard slope, extend- 
ing to ellipse only. Note that #1 is 
slightly to the right but parallel to the 
left-hand guide Hne and therefore is 
not tangent to ^2. #4 extends to right 
guide line. Note that extreme width of the 
numeral is from starting point of '^2 to right- 
hand point of tangency. 

Eight. 4 strokes. The outline of the numeral'^ 
is made up of two tangent ellipses. The 
lower half of the numeral is similar in 
outline to the upper half but slightly co 
wider. Note the similarity to 5 (see 

page S3)- 

Three. 4 strokes' 
Consists of portions 
of two ellipses of the same dimensions. 
Note that less of the upper ellipse is 
used than the lower ; this is in order that 
the numeral will not appear top heavy. 
The J is similar to the 8 (see this page) . 
Two. 4 strokes. 
The upper half of 

the numeral consists of part of an 

ellipse, which is one-half the figure 

height and the full figure width, fti 

and 1^3 are both tangent to left guide 

Hne. Note the curvature of S3 and that '■^\ 

begins lower down than on the numeral j 

(see this page). 






6o ELEMENTS OF DRAWING 

45. Sheet D. The purpose of this sheet is to teach the 
beginner the characteristics of the numerals and to give 
practice in rnaking them. Locate the numerals on the sheet 
as shown in Fig. 43. 

The slope of fractions must be the same as that of the alphabet; 
for example, take any ordinary fraction, say, five-eighths, the 
eight is not vertically below the five, but a standard slope line 
drawn through the center of the 5 passes through the center of 
the 8. The line separating the numerator from the denominator 
must always he a straight line parallel with the line of printing. A 
sloping dividing line may lead to error in reading a fraction. The 
figures in the numerator and. in the denominator must never 
touch the dividing line. The total height of a fraction should 
be about one and one-half times the height of whole numbers. 

Follow specific instructions given for preceding sheets in so far 
as they apply to this sheet. 

The title of sheet D is NUMERALS. 

46. Sheet E. The purpose of this sheet (see Fig. 44) is to 
give practice in lettering of a size suitable for notes on working 
drawings. 

Follow specific instructions given for the preceding sheets in so 
far as applicable. 

The title of sheet E is LETTERING. 

Specific Instructions for Inking Sheet E. Tack down the 
approved penciled sheet on the drawing board, and carefully ink 
each letter in the order in which they come. Clean the pen 
frequently and maintain a steady and even pressure on the pen 
point. Extra care must be taken in inking this sheet other- 
wise it is liable to be spoiled. 

47. The Small (or Lower-case) Letters of the Inclined Gothic 
Alphabet. In studying characteristics of the lower-case alphabet, 
carefully read § 34, page 37, and remember that the direction 
and order of strokes is of prime importance. As in the case of 
free-hand capital letters, all strokes which are horizontal or nearly 
so are made toward the right, while all others are made down- 
ward or toward the draftsman. This avoids the possibility of 
catching the pen point in the drawing and splashing the ink. 



LETTERS, NUMERALS, AND LETTERING 



6i 




62 



ELEMENTS OF DRAWING 



-^ 



i: 



:=r$- 



lil 



^- 



-9- 



x: 



==E- 



-£■ 



-^- 



i: 



=*= 



:5: 



■?=- 



:i: 



-:- 






:p^i^: 



-^- 
Z- 

■4i- 

-Z: 



4.- 



P 

id: 



W- 



±^ 



~-t 



-^-h- 



1- 



^: 



it 



z 

t: 



is;- 

ft! 

El: 



2: 



^: 



:^: 



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3: 



13: 



t]- 



-^ 



=S- 






4^ 

I 



LETTERS, NUMERALS, AND LETTERING 



63 



This alphabet requires a total height of eight blocks for the 
model letters, but in practice only four horizontal guide lines are 
necessary. These Hnes are numbered from the bottom to the top. 
Thus, iti limits the letter when its stem (seepage 37, § 34) extends 
below the body of the letter, as in g, j, p, g, y; ^2 limits the bot- 
tom of the body; 4l3, the top of the body; and #4, the stems when 
they extend above the body, as in h, d,f, k, h, and /. The distance 
between the first and second lines and between the third and 
fourth lines is two spaces, or one-half of that between the second 
and third lines. The height and width of a, c, e, n, o, u, and v is 
the same and is equal to four unit spaces. 

The letter is similar to the sloping 
ellipse described in §40, page 50, and 
makes up wholly or partially the outhne 
of all letters having a body more or less 
elliptical. The horizontal and the slope 
guide lines form a parallelogram and 
the horizontal center line intersects these guide lines at their mid- 
points, which determine the touching points of the ellipse, but 
the sloping center line runs from the lower left hand corner to 
the upper right hand corner [see Fig. 40 (c), page 51]. Thus the 
small oval letters "tilt" more than the capital oval letters, though 
the slope of the letters appears the same. Consequently the 
small letters are more in harmony with the capital letters 
previously described. The small is similar to the capital O 
(see page 51). 

Letters a, d, g, and g differ as to the length and position of their 
\(,. |_v(,« stems. All these stems have standard 
slope and are tangent to the elliptical body 
at the same corre- , 
spending point. ^ 
G. L. The vertical height 




iG.L 





of the elliptical ^ 

body (or lobe) is }_ 
equal to its width and is the same as for 
the (see this page) . The body of the a, T" '^""l 

d, g, and g should be made with two strokes, as shown; stroke 
#3 Hes along the slope guide hne. 



64 



ELEMENTS OF DRAWING 




but stroke #3 continues to guide line #1. 



d repeats a, except that stroke #3 begins 
at guide line ^4. 

g repeats a but h — 4- 

stroke #3 continues 
with a sweeping 
curve to guide hne #1 . 

q exactly repeats 
the a construction 




MH 



Letters b and p. 
-4— 




The stem of the b 
is the first stroke 
and coincides with 
the left-slope 
guide line; stroke 
ft2 ends at the 
touching point of 
the ellipse and 




left-slope guide line; stroke #3 continues to the stem. 
p differs from the b only in the position of the stem. 
Letters c and e. V 

The c has the same / 

height and width ^-^1 
as the (see page 
63), but the open- 
ing in the ellipse is 

such that strokes ^" h— 4— j K-:^— ^1 

#2 and S3 begin at different touching points on the right-slope 
guide line. The small c is similar to the capital C (see 
page 52). ^ 

The e differs slightly from the c in that stroke #2 ends on the 
horizontal center Hne ; stroke #4 starts from the point of tangency 
of stroke fti, and, following the center Hne, joins stroke ^2. 

Letters n, r, h, and m. The curved 
portion of the n consists of the upper 
portion of the ellipse exactly as that of 
the u consists of the lower portion of 
G.L. the 0. Stroke fti is standard slope; 
stroke #2 ends where the ellipse comes 




LETTERS, NUMERALS, AND LETTERING 



65 




tangent to the left-slope guide line, and 
stroke #3 follows the guide line from the 
point of tangency. Strokes fti and #3 must 
be parallel, beginning at their points of 
tangency with the ellipse. 

The r is the same as the left half of the 
n except that stroke #2 continues along 
the top guide line a short distance. 

The h differs from the n only in the length 

— of the stem, or stroke |fi. Note that though 

the first three strokes of the 

m are similar to those 

of the n, the width is T~3 





different; strokes #4 4t- 
. -'^-^;and #5 are a repetition of 
#2 and #3. All stems are parallel and 
have standard slope. 

Letters u and y. The curved portion of the u consists of the 

lower part of the 
ellipse, exactly as 
that of the n con- 
sists of the upper 
portion of the 0. 
Note that stroke 
#3 continues to 
guide line #2. 

y repeats the u, but stroke S3 continues to guide line #1 
exactly as in the g. (See page 64.) 

Letters I, i, k, tj, andj. The / is a simple standard slope line 
drawn toward the draftsman and is six spaces high. 

The i is a single stroke of standard slope, and the dot is 
placed exactly where the stem if extended would cut the hori- 
zontal #4. 

The k has a standard slope line as stroke fti ; stroke #2 starts 
on the horizontal guide line ^3 but to the left of the slope guide 
line, so that the latter is not so wide at the top as at the bottom; 
stroke S3 begins helow the middle of stroke ^2, and extends to the 




66 



ELEMENTS OF DRAWING 



horizontal guide line #2, giving the lower part of the letter the 
standard 4-space width. 





The / is five spaces high and has the standard slope. Stroke 
jt2 is the horizontal cross-bar which coincides with horizontal 



1 1 ; 








^( 


?- 


/ 




/ 


t- 


\ 






i 


k- 


>^ 


/ 


■»-.» 


T 


_ 


-2- 






/ 




f 






/ 






/ 






1 




/ 




/ 










/ 




/ 








/ 


/ 










/ 


-i 


2 


A 
*1 ■ 












guide Hne ^^3 and which is two spaces long but is not bisected 

by the stem of the letter. 

The / repeats the t except that by adding stroke ^^ the letter 

is brought to the height of the /. 

The j repeats the i, but is carried to the horizontal guide Kne 

^1 by adding a curve with a sweep one-half space less than the 

tail curve of the g and that of the y. (See pages 64 and 65.) 

Letter s. The j is formed in three 
strokes. Stroke fti is a double and 
reverse (ogee) curve which is horizon- 
tal at the top, bottom, and the middle 
for a very short distance. Strokes #2 
and #3 are short curves from left to 
right. If the bottom oval of the 

letter should be completed it would be four spaces wide, while 

the upper oval would be only three and a half, thus making the 




LETTERS, NUMERALS, AND LETTERING 



67 




letter wider at the base than at the top. The small 5 is similar 
to the capital S. (See page 53.) 

Letters v and w. The v contains the only vertical line in this 
alphabet which 
is stroke #1. It 
has full -letter 
width of four 
spaces at the 
top. The small 
V is similar to 
the capital V. (See page 46.) 

Stroke #1 of the w is not the same as stroke fti of the v, nor 
is it twice as wide as the v; that is, the w is not made up of 
two v's. The small w is similar to the capital W. (See page 47.) 

Letter x. The x is made with two 
strokes, intersecting slightly above the 
middle of the sloping center line. The top 
is three and a half spaces wide, while the 
bottom width is the standard four 
spaces. Note that this slight difference 
^' r ^"H in top and bottom width is the same with the 
s and z. The small a? is similar to the capital X. (See page 46.) 

Letter z. The z is made up of three 7 n ; 

strokes. The top and bottom of the letter * "• ^ 

have the same widths as that of the x 
and s. The small z is similar to the 
capital Z. (See page 47,) 

48. Sheet F. The exercises on this sheet 
(see Fig. 45) give practice in making the 
small letters of the Gothic alphabet and afford an opportunity to 
study in detail the characteristics of each of the lower-case letters. 
For detailed description see § 47, page 60. Note especially the 
relative size of capitals and numerals used with this alphabet. 

This sheet is to be inked but is to be perfected and approved 
in pencil before inking is done. 

Follow the specific instructions given for preceding sheets as far 
as applicable. 

The title of sheet F is LOWER-CASE LETTERS, 





U — jf.- 



68 



ELEMENTS OF DRAWING 




LETTERS, NUMERALS, AND LETTERING 69 

49. Designing Headings and Titles. A very quick method 
of laying out the title is to sketch the lines of lettering on 
transparent paper of good quality and then transfer them in 
their proper relative position. The transferring is best done by 
blackening the back of the paper upon which the lettering is 
sketched, using a soft lead pencil sharpened to a chisel point and 
held flatwise. The paper is next placed in its proper position 
on the drawing and the outline of each letter carefully traced 
over with a moderately sharp pencil; this transfers the letters 
in dim lines. These outlines will not be so true as the original 
lines and must be gone over with a pencil before being inked. 

After a httle experience, a simple title can b.e made directly 
on the drawing by using horizontal guide lines and arranging the 
lettering symmetrically about a vertical center line. This letter- 
ing should be sketched in very lightly at first, and when correct 
the entire title should be retraced in pencil before being inked. 
When lettering a drawing if a name or a 
sentence cannot be printed in a horizontal 
line, the proper way to have the inclined 
Iett:ering read is shown in Fig. 46. 




50. Sheet G. The purpose of this sheet 
(see Fig. 47) is to give practice in laying out 
Fig. 46.— Direction in the bill of material and the title for a drawing, 
which Inclined Lines^of ggf^^.^ beginning work ou this shcct read 

Lettering Should Read. o y 

carefully § 49, this page. This sheet is graded 
upon the quality of the lettering, and the accuracy shown in 
locating the different lines of lettering. 

Follow specific instructions previously given in so far as appli- 
cable. 

NOTE. The straight border and limiting lines of the title 
form can be drawn by use of a straight edge, but they should be 
made neatly and in the exact location as shown in Fig. 47. 

The title of sheet G is TITLE FORM. 

51. Examination on Chapter II. Lay out a sheet of vertical 
Gothic letters or any other sheet of lettering assigned. Prepare 
for examination on. the principal subject matter of this chapter. 



70 



ELEMENTS OF DRAWING 



WansJoaSpS 



^ 



CO- 

s; 



-y 



dh 







(Qlyt-.^- 






I 

I. 



M:r. 
co--^; 



©25- 



CHAPTER III 

MECHANICAL DRAWING AND DRAFTING ROOM 
PRACTICE 

52. Introductory. The difficulty of describing an object so that 
its form and proportions can be completely understood and the 
object made by following the written description will be appre- 
ciated if such a description is attempted with reference to some 
comparatively simple object. The art of drawing is made use 
of to overcome these difficulties and drawing might be considered 
a " short hand " method of expressing form and proportion. The 
field of usefulness of drawing is very broad and the value of being 
able to draw and to read drawings becomes more apparent when 
it is reahzed that practically all buildings and construction, as 
well as most manufactured articles, were planned and drawn 
before their construction or manufacture was started. In study- 
ing this subject, the beginner should make every effort to become 
proficient in the reading as well as in the making of mechani- 
cal drawings. It is probable that most persons will never be 
called upon to make any but the simplest, of drawings, but all 
those connected in any way with engineering work must be able 
to read them, and the ability to read drawings quickly and cor- 
rectly is of the greatest value. There are several branches of 
drawing, and the branch to which the reader has likely become 
most accustomed is perspective drawing or, in other words, draw- 
ings which represent an object in a single view, as it would ap- 
pear to the eye or in a photograph. A perspective drawing, 
however, is usually difficult to make and does not offer the 
possibilities for recording dimensions and other information which 
is often necessary to the engineer and which can be easily re- 
corded on a mechanical drawing. 

A mechanical drawing does not represent an object by a single 
view, as it would appear to the eye or in a photograph but repre- 
sents it by a series of pictures termed "projected views " which 

71 



72 



ELEMENTS OF DRAWING 



will be explained later. Each of these views represents some 
" face " of the object as it would appear if it actually existed in 
space, its appearance assumed to be unaffected by the laws of 
perspective. See § 53, page 73. 

Briefly stated, a mechanical drawing must contain complete 
and absolutely accurate information of what is desired; every 
line on the drawing should be a fixed and measurable distance 
from every other line and should stand for something definite; 
the views, lettering, and dimensioning must be well arranged, 
and neatly and accurately done, so that the drawing as a whole 
will be exactly understood and present a pleasing and business- 
like appearance. 

When lines cannot express ideas in a plain, direct, and un- 
mistakable manner, abbreviations, symbols and printed notes 
must be used so that those who are to read or interpret the 
drawing will be in possession of all the information necessary to 
carry out every detail of the designer's or draftsman's wishes 
without further instructions, either written or spoken. 

In just so far as a drawing fails to contain all necessary infor- 
mation in the best form possible it is unsatisfactory, regardless 
of how well it may conform to the principles of mechanical draw- 
ing or the degree of precision and elegance with which it has 
been made. 

Symbols on a mechanical drawing usually consist of printed 
abbreviations or conventional signs, which signs are more easily 

drawn than the true form of the object 
to be represented. Thus, instead of 
representing screw threads in their exact 
form, as shown in Fig. 48, and which 
would be difficult and tedious to draw, 
especially on a small scale, the conventional method of rep- 
resenting ordinary screw threads, as 
shown in Fig. 49, is widely made use 
of in practical drawing rooms. 

The relation of parts to one another, 13 Thds. per inch. l. h. 

,. r . j-i r 1 Fig- 49- — Threads Conventionally 

processes of manufacture, the final represented. 

finish of surfaces, and similar data are indicated by notes, 

abbreviations and conventional signs. 




Fig. 48. - 



- V-Thread, represented in 
Trued Form. 




MECHANICAL DILWVING AND DRAFTING ROOM PRACTICE 73 

The printed matter consists of dimensions, notes of instruction 
or specifications, names of parts, titles, and similar information. 

Each of these three divisions — the drawing of the views, the 
application of conventional signs, and the composing and 
printing of notes, titles, dimensions, etc., — is in a way of equal 
importance, and it should be remembered that mechanical 
drawing, as it is generally understood and appHed, especially in 
the manufacture of machinery, etc., is not intended to produce 
artistic effects, but to give instruction and to convey information 
of a definite character in the simplest way possible. 

53. Projection and Projected Views. Mechanical drawing 
is based upon the principles of orthographic projection, and a 
knowledge of the fundamental principles of orthographic pro- 
jection is necessary in order to understand even the simplest 
drawing. A short discussion is given here and a more extended 
discussion of this subject will be found in the authors' book on 
"Elements of Descriptive Geometry" and in other books on the 
same subject. 

Orthographic projection consists in representing the form of an 
object as it would appear if projected upon two or more planes 
(termed planes of projection) at right angles to one another. 
The projecting is assumed to be done by rays of light respec- 
tively perpendicular to these planes and extending from the 
planes to the points on the object being projected. 

One plane of projection is assumed in the position of an ordi- 
nary wall (i.e., vertical) and is termed the vertical plane of pro- 
jection, the other occupies a position corresponding to the floor 
(i.e., horizontal) and is termed the horizontal plane of projec- 
tion. Both vertical and horizontal planes of projection are as- 
sumed to be transparent, and every ray of light which extends 
from the vertical plane to a point of the object will be horizon- 
tal because all of these rays are perpendicular to the vertical 
plane; similarly the rays which extend from the horizontal 
plane to the object will be vertical. This is clearly illustrated 
in Fig. 50, where a part of the lathe is shown projected. The 
object which is shown projected is called the Tool Rest Sup- 
port Slide and is shown in perspective in Fig. 112, page 150. 



74 



ELEMENTS OF DRAWING 



A careful study of this illustration will make clear the process of 
projecting in space. To produce a drawing by the principles 
of Orthographic Projection it is necessary to make further as- 
sumptions in order to establish a relation between the trans- 




Fig. 50. — Illustrating the Method of Orthographic Projection 
by the Use of Transparent Planes. 




:k] 



(a) — Showing the Plan, Front and Side 
Views Brought into a Single Plane. 



(b) — Arrangement of Views 
Ordinarily Used in Making a Drawing. 



Fig. SI. — Usual Relation of Views on a Flat Surface. 

parent planes at right angles in space and the drawing paper 
which is in a single plane. It is seen that the object is behind 
the vertical plane and helow the horizontal plane, and this is 
termed third angle projection. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 75 

Assume that after the views of the object are projected 
upon the planes these planes are unfolded so as to be brought to 
a single plane or flat surface, as shown in Fig. 51. This opera- 
tion brings the top-view above the front-view, and the right- 
side-view to the right of the front-view. By connecting projec- 
tions of corresponding points of the different views with straight 
dashed lines (as shown), it will be found that these lines are 
perpendicular to the lines (G-L and Gi-Li) which mark the edges 
of the planes of projection. These dashed Hues serve to connect, 




(a) — Showing Plan and Front Views " Folded " into 
the Plane of the Side View. 




(b) — Showing Front and Side Views " Folded " into the Plane of the Plan View. 
Fig. 52. — Various Arrangements of Views. 



from one view to another, points which are projections of a single 
point on the object represented. They are the same length as the 
projecting rays of light and represent them on the drawing paper. 
The relative position of the different views as shown in Fig. 51 
is a very common arrangement in practice, but the arrange- 
ments of views as shown in Fig. 52(a) and 52(b) are equally 
correct and may be used if for any reason they are found more 
convenient. The top view is known as the plan, and the side 
or front views as the side elevation or front elevation. 



76 ELEMENTS OF DRAWING 

54. Conventional Lines. If all the lines of a drawing were 
identical in character, that is, unbroken throughout their 
length and of the same weight,'^ the drawing would be lacking in 
contrasts and would be difficult to read. This difficulty is 
overcome by using lines of different construction and weight 
for different purposes. For example, solid unbroken lines 
(called "visible lines") of fair width are used to represent 
visible parts of an object; fine lines (called "invisible lines") 
composed of short dashes are used to represent invisible parts. 
Dimension lines are unbroken (except for the dimension figures) 
but are not so prominent as the lines representing visible out- 
lines of the object. 

The meaning of the construction of the various lines is 
given below, but no single rule can be stated as to the proper 
weight of the different classes of lines since this depends on 
circumstances. 

The visible line is an unbroken^ heavy line used to represent the 
outline of the object and the surfaces that are in full view 

Fig- 53. — " Standard " Visible Line. 

of the draftsman. The weight of the line must be varied at 
times, depending on the size and the accuracy required of the 
drawing, but the standard weight is shown in Fig. 53. 

The invisible line is used to represent the parts of an object 
which are hidden or invisible to the draftsman. Such lines are 
broken into short dashes about one-eighth inch long, separated 
by spaces of one-half this length, and are only about two-thirds 



Fig. 54. — " Standard " Invisible Line. 

the weight of the visible lines. When an invisible line is very 
short, the dashes and spaces rhust be shortened accordingly. 
Dashes must be made of one length and spaces of another, the 
spaces always being smaller than the dashes (see Fig. 54). 

^ The weight of the line determines its prominence. Variation in weight 
is secured by making the line of different widths if drawn with ink, and 
by making it hghter or darker in color by varying the pressure and hard- 
ness of the lead if drawn with a pencil. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 77 

Section lines (see Fig. 55) are drawn parallel and usually close 
together (say, Jg-" to ^") and covering those areas which are 
assumed cut and exposed to view. They are light weight con- 
tinuous lines in construction. (See Fig. 63, page 81.) 

Fig. ss. — " Standard " Section Line. 

Dimension lines (see Fig. 56) are for the purpose of indicat- 
ing the limits between which dimension figures apply. Dimen- 
sion lines are drawn light weight and are unbroken except for 

-^ /8- ^ 

'2 

Fig. s6. — "Standard" Dimension Line. 

a distance, usually in the center, to allow for the dimension 
figures. Under no circumstances should this line pass through the 
dimension figures. 

An arrowhead is drawn at the end of a dimension line to 
indicate its extremity and the place to which the dimension 
applies. 

Arrowheads appear much better when drawn long, sloping, 



^r 



(a) Correct. (b) Incorrect. 

Fig. 57- — Arrowhead. 

and narrow, as shown by Fig. 57(a), and they should not be 
drawn spreading, as shown by Fig. 57(b). 

Reference lines extend out from a part to be dimensioned to 
receive the arrowheads at the ends of the dimension lines. They 
consist of groups of three dashes — two short and one long — 
repeated as often as necessary to make the line as long as re- 



Fig. 58. — "Standard" Reference Line. 

quired. The line should begin with the two short dashes and 
end with the long one, and the relation between short dashes, 
long dashes, and spaces is the same as in center lines. (See page 
78.) A short space should always separate the reference line from 
the object. Fig. 58 shows the standard reference line. 



78 ELEMENTS OF DRAWING 

The center line is a line around which a sketch or drawing 
is "built," and is usually an axis of symmetry. It is composed 
of short and long dashes. The short dashes are about one- 
eighth inch long, and the length of the long dashes will depend 
on the size of the drawing. The space separating long and 
short dashes is about one-sixteenth inch. (See Fig. 59.) 



^ 



Fig- 59- — "Standard" Center Line. 



The center line of a part not detailed is often shown on a 
drawing in its true relative position to the parts that are drawn. 
In such a case the symbol C^ is written across the center line of 
the part not detailed, but this symbol is not used on center 
lines of parts that are drawn. Thus, on part No. i of drawing 
C-ioi (see page 118, Fig. 82) the center line of the shaft is not 
marked, but the positions of the bearings are located by drawing 
their center lines and marking them ^ OF BEARING. 

Some drawings do not require center lines, while others may 
require several, depending usually on the number of axes of 
symmetry. The center-line construction is also used to indicate 
the location of a cutting plane in making a cross-sectional view, 
and the two should not he confused. 

All finished lines, whether drawn free-hand or mechanically, 
with pencil or with ink, must be : 

{a) Clear cut. 

(b) Free from waves. 

(c) Of the same width throughout. 

{d) Colored to the same degree throughout. 

A line is clear cut when the edges are free from irregularities, 
that is, when the outer edges are not " ragged " or " sketchy." 

A line is free from waves when it does not deviate locally 
from the general direction it should follow. Both the wavy and 
the ragged free-hand lines usually result from holding the pencil, 
or particularly the pen, with such a tense grip as to cause the 
hand to tremble. Hold the pencil or pen easily, as you would 
in ordinary writing. 

A line is of unvarying width when the outer edges run paral- 
lel throughout its length. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 79 

A line is colored to the same degree (i.e., of even color) when 
the coloring matter (such as lead or ink) is evenly distributed 
throughout the line. To avoid making a pencil or ink line 
appear dark at one point and light at another, that is, variable in 
degree of color, apply even pressure in making the finished line, 
and in inking maintain a uniform flow of ink by frequently 
cleaning and refilling the pen. 

55. Sectioning and Sectional Views. If an object has hollow 
portions it is often necessary to know the exact form and the 
dimensions of the interior. 

Since invisible portions of an object are represented on draw- 
ings by means of broken lines, views which represent the exte- 
rior or visible portion and at the same time attempt to show the 
interior form of an object are frequently complicated and hard to 
read. To overcome this difiiculty it is often convenient to im- 
agine the object cut open with a saw [see page 80, Fig. 60(a) 
and 60(b)] and then represent it as if the plane of the cut MN 
were an outside surface of the object. [See Fig. 60(c).] 

Such a view of an object is termed a sectional view, a cross 
section, or simply a section of the part. If a section is taken 
in the direction of the length of an object, it is termed a longi- 
tudinal section; if taken perpendicular to the length, it is termed 
a transverse section. 

A complete section is not always assumed in a single plane, but 
may be made up of partial sections in several planes. A built- 
up cross section is intended to give information in such a way 
as to make it unnecessary to draw several cross-sectional views 
or perhaps a complete view of the object. In Fig. 61 the cut- 
ting planes move along the line HPST and the section should 
be referred to as the section HPST. 

The method of accurately determining complicated sections 
in true projection is beyond the scope of this work and is ex- 
plained more fully in the authors' book on " Descriptive Geom- 
etry " and in other books on the same subject. 

In order to make sectional views easily understood, the dif- 
ferent kinds of material assumed to be cut are sometimes in- 
dicated on the drawing by conventional methods. The usual 



8o 



ELEMENTS OF DRAWING 





/ z&- "', 


o o 


/ 


«»«: !, i- X 


\/ 


/^^// 




/ 


/ 





s 


s 




8 


s 


1 
^ 


1 


xVvWwwWw 1 



H 


o o 


to 


M.2. 


a< 


fl •Q 


n 


'a o 






lU 

a 


S: 


m 


<U bjo 





!1 






rn 


« a 








.Q 


hfo 




d. 




MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 8l 



method is termed sectioning and consists of various combina- 
tions of spacing, and light and heavy weight Hnes drawn parallel 
and covering the area which represents the surface assumed to 
be cut and exposed to view. No uniformity exists in practice 
as to the combination of lines and spaces that shall represent a 
particular material. Those combinations given in Fig. 62 are 
fairly general in their application, but it is readily seen that, 
because of the great variety of materials in use and the fact that 



GMST IRON 




VmouCHT IRON 

Vj 





BRASS OH 
COMPOSITION 



LEAD OR 
BABBITT 






Fig. 62. — " Conventional " Sectioning. 

new materials are constantly being introduced, it is better 
practice to use only the simple parallel lines [see Fig. 63 (a)] 
and then designate the ma- 



terial by writing its abbre- 
viation (seepage 103, § 67) 
on the ruled surface or in 
some other simple manner. 
Where a number is used 




(a) Ordinary Sectioning. 



(b) Sectioning Adjoining 
Pieces. 



Fig. 63. — Sectioning. 

to indicate a material, it has the advantage that the number can 
also represent the quality, heat treatment, etc., or, in the case 
of alloys, the composition. The number therefore does not 
only represent the name of the material but also its properties — • 
both physical and chemical — and in reality is a specification 
number. A further advantage of this method is that, should 
the material originally called for prove unsatisfactory, as is 
frequently the case, a change in the number can be made on 
the drawing without erasing the section lines. 



82 



ELEMENTS OF DRAWING 



Section lines of adjoining pieces [see Fig. 63(b)] are drawn 
in different directions, if possible, so as to more clearly define 
the limits of the parts. 

Section lines should be drawn at 45° to the horizontal when- 
ever possible, and should be made about one-half the weight of 
the lines used to represent the outline of the section. To section 
an area evenly requires practice and a steady hand. Beginners 
usually make the mistake of drawing the section lines too close. 
Also the tendency is to vary the distance between section lines, 
usually increasing the spacing as the work proceeds. Such sec- 
tioning is unsatisfactory, and can be avoided by glancing back 
over the completed area for each eight or ten lines drawn, thus 
bringing to mind the original unit of spacing. If a section line 
has been drawn too far from the preceding one, the next line 
should be drawn at a distance less than the unit spacing; this 
has the effect of giving an even appearance and the normal 
spacing should then be continued. 

The spacing between section lines should be tV" to |", depend- 
ing upon the size of the cross section, but must be the same 
throughout the area of any single part being represented in sec- 
tion. To insure uniform spacing, draftsmen sometimes use 
section liners. The simplest form, and one easily made, is 
shown in Fig. 64. It consists of a small 
straight-edge cut out to receive one side 
of the triangle. The length of the slot 
portion is equal to the length of the side 
of the triangle plus the approximate 
distance desired between the section 
lines. To use this device, place it on 
Fig. 64. — Section Liner. ^-j^g drawing with the triangle against 
the left-hand stop, as shown in Fig. 64; draw a line along 
the slope side; hold the triangle stationary with the fingers of 
the left hand, and with the thumb move the strip to the left 
until it is stopped by the triangle. Next hold the strip sta- 
tionary and slide the triangle until it comes in contact with 
the left-hand stop of the strip, and draw the second line. This 
process is repeated until the sectioning is completed. When 
the section is very large, the section lining is sometimes placed 




MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 83 

at the edges only, as this saves time and usually gives a better 
appearance; in such cases the distance between the section lines 
would be increased somewhat. 

Sectional views may be drawn in any suitable position on 
the drawing, but it is always best to locate them as close to the 
place at which they are taken as is convenient. To indicate 
the location of the section, a Kne must always be drawn across 
the original view of the object, and the extremities of the Kne 
(which represents the cutting plane) should be lettered as shown 
in Fig. 85, page 123. 

It is not always necessary to draw the cross sectioning over 
the entire surface that lies within the cutting plane, and in 
general such details as a shaft, key, bolt, gear tooth, rib or arm 
of a wheel, are not sectioned. 

Where a part shown in section is symmetrical about a center 
line, such as a part turned on a lathe, a half or a quarter longi- 
tudinal section, together with an end view, is often the best choice 
of views. Thus, a drawing of the Tail Stock Spindle (see Fig. 
103, page 144) or the Shell (see Fig. 104, page 144) would usually 
consist of an end view and a top or side view shown in section; 
that is, the Spindle is assumed to be sawed in two lengthwise, 
the front or top half removed, and a drawing made of the remain- 
ing half as it appears when looking directly at the cut surface. 

When a drawing is made of an object assumed to be so cut 
that one-fourth of the piece is removed, the view is termed a 
quarter-section view. 

Sometimes by turning up a section directly on the first view 
space is saved and a second view of a part is unnecessary. In 
such cases all the lines of the original view must be drawn in, 
even though they may conflict somewhat with the lines of the 
turned up section. (See Key shown in Fig. 82, page 118.) 

56. Number and Arrangement of Views. There is always a 
choice of views, and those views should be made which convey 
the greatest amount of information consistent with clearness. 
In determining the number of views required, the purpose of 
the drawing, the form of the object drawn, and the character of 
the views must all be considered. The rule to be followed as 



84 ELEMENTS OF DRAWING 

to the number of views is that there shall be the least number 
made to accomplish the pm-poses of the drawing. In general, 
three views of an object are sufficient to illustrate its form and 
the processes necessary in its manufacture. If, however, its 
construction is complex, it may require sectional views in ad- 
dition to the three general views ordinarily taken. If the part 
is quite simple and symmetrical, — as, for example, a washer, 
bolt, screw, shaft, plain key (see Fig. 82, page 118), — a single 
view is sufficient. The draftsman should imagine himself read- 
ing the drawing, and make as many views (and no more) as 
are necessary to give complete information in a clear and 
unmistakable manner. While making or checking a drawing if 
the question arises as to whether certain views or cross sections 
are needed in order that the drawing may convey all information 
necessary, these views or sections should always be drawn, for 
it is reasonable to assume that any point of uncertainty not fully 
cleared up by the draftsman or checker leaves the way open for 
those using the drawing, especially for the first time, to make 
mistakes. An effort on the part of the draftsman or checker to 
rush work or "save" time often leads to costly errors on the part 
of those who must work with the drawing, besides causing a loss of 
time by each person who must read the drawing. A note should 
be used when it will save drawing a view. In general, several sec- 
tions are preferable to a single view containing many dashed lines. 

The arrangement of the views must be such that their relation 
to one another will be what is technically termed third-angle pro- 
jection (see page 74, § 53). Sectional views and other auxiliary 
views should be placed close to the main view of the part which 
they partially represent. 

' Where practical the main views of an object should represent 
it in a similar position to that which it will occupy on the ma- 
chine, that is, a part should not be represented upside down, etc. 

The different views should be arranged symmetrically on the 
sheet, in order that space may be used to the best advantage and 
that the drawing as a whole may present a pleasing appearance. 

This can be accomplished best by blocking out the sheet 
with free-hand rectangles, drawn to scale, to include each view 
(see page 93, § 61). These should be sketched in very lightly, 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 85 

and, after provision has been made for all the views, if the rec- 
tangles are not well distributed they can be easily rearranged. 

57. Detail Drawings. A detail drawing is one which repre- 
sents a single part and contains all information necessary for its 
manufacture. Before a detail drawing is made, therefore, an ex- 
perienced draftsman will determine exactly and to the minutest 
detail the purpose of the finished part and the shop operations 
necessary to produce it. It often occurs that the draftsman 
knows exactly what is wanted in the finished part but has not 
had sufficient shop experience to know the best method of produc- 
ing it. In such cases this information should be obtained from 
a reliable source before the drawing is carried too far. Generally 
a single detail drawing serves for all departments of a manufac- 
turing plant, but it may happen in complex work that different 
details are required for the different classes of workmen, such 
as the pattern maker, the blacksmith, the machinist, etc. Such 
drawings give the dimensions and notes required only by the 
particular class of workmen for whom they are intended. 

The number of parts detailed on a single sheet will depend 
on circumstances, but it is becoming more common to detail each 
part on a separate sheet. This method has the advantage that 
fewer workmen are affected in case a drawing has to be recalled 
for any reason. Also, as the drawing can be easily and quickly 
obtained, the chances of costly mistakes are lessened in case a 
change must be made on a part. In cases where an article is 
standard and is produced in great quantity it is sometimes 
advisable to represent a part on several sheets called operation 
sheets, that is, a drawing which shows only the operation to 
be performed on the part by a single workman. In establish- 
ments where a system of representing several parts on a single 
sheet is practiced it is customary to group parts in a logical 
manner; for instance, parts which fit together may be detailed 
on the same sheet, say, in the case of the lathe the details of the 
Headstock might make up one sheet; parts made of the same 
material, such as cast-iron parts, might be grouped; or parts 
which are manufactured by similar processes, and hence in the 
same shop department, are detailed on the same sheet. If parts 



86 ELEMENTS OF DRAWING 

which fit together are detailed on the same sheet they are more 
easily checked, but in practice it is often difficult to maintain a 
fixed system of grouping. Certain advantages are to be gained 
by the beginner in grouping detail drawings and hence several 
parts will be shown on a single sheet in this course rather than 
each part drawn on a separate sheet. 

In making a detail drawing, roughly "block out" in very 
light lines the different views in their approximate relative loca- 
tion on the sheet lefore beginning the actual pencil drawing. 

It is usually better to work up all the views of a part at the 
same time rather than to endeavor to complete one view and 
then pass to the next. As a rule, one part should be detailed 
completely, including all its views, dimensions, notes, etc., 
before the detailing of another part is started. 

58. Assembly Drawings. The detail drawings show the form 
and size of each part but give no idea how the various parts 
fit together or how the machine or structure as a whole will 
appear. The assembly drawing illustrates the general design 
of a machine or structure and contains information which en- 
ables a workman to sort out the finished parts and assemble 
them into the machine. The assembly drawing is, therefore, a 
representation of the completed machine or structure with all 
its parts collected and arranged in their proper relation to 
one another. It should he drawn part by part from the detail 
drawings and serves as a last check that all parts fit together. 
Such drawings may show some detail, but too much of the inside 
construction should not be shown (in dashed lines) or the drawing 
may be difficult to read. If the machine is complex two or more 
views and cross sections through several parts may be required, 
in order to give all necessary information and still avoid too 
much dashed-line construction. Such minor parts, as bolts, nuts, 
screws, keys, etc., are seldom drawn in detail upon the assembly 
drawing, but their position is usually indicated by center lines. 

Only over-all and important main dimensions should be 
given on assembly drawings. It sometimes adds to the value 
of an assembly drawing to give parts a reference number or 
letter so that they can be easily referred to. See page 104, § 69. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 87 

59. Conventional Methods. As has been stated elsewhere, 
the purpose of a mechanical drawing is to give instruction and 
information, and not to produce elaborate picture effects. For 
this reason it is often best to represent an object by as few lines 
as possible if in doing so clearness is not sacrificed. Such abridged 
methods of representing forms and constructions on a drawing 
are termed " conventions " or '' conventional methods " and are 
universally used to represent details that are of frequent occur- 
rence, such as screws, bolts, threads, etc. 

Conventional methods may be used in several ways, for ex- 
ample, as a drawing which approximates the form of the object 
being represented; cross-sectioning, shown in color or by lines 
which symbolically represent the materials ; methods of represent- 
ing the planes in which an object is assumed to be cut; the path 
and the direction of motion of a moving point; shop operations, 
such as the finish of surfaces, etc. Unfortunately no list of 
conventions can be universally adopted, and upon entering the 
employ of a company the draftsman must study and adhere 
to their particular system. Fig. 65, page 88, illustrates common 
conventions, some of which are used in this course. 

Group A, Fig. 65, sho^^rs the following conventions: 

1. Method of representing a shaft of circular section so that 
space can be saved on the drawing. This method of repre- 
senting an object, as if a portion were omitted, cannot be used 
unless the form of the portion omitted is exactly the same as 
the part shown. Thus, that portion of a shaft with a keyway 
could not be omitted in any way that would leave any infor- 
mation as to the dimensions and location of the keyway lacking. 

2. Method of representing a bearing. Note that the distance 
between bearings is given from the center line of one to the 
center line of the other. 

3. Method of representing the broken end of a timber viewed 
from the side, also method of showing cross section of timber. 

Group B shows the following conventions: 

I. Method of representing a long hollow part and contracting 
the drawing lengthwise. The break differs from that of the 
shaft in that the proportional thickness of the shell is shown. 



88 



ELEMENTS OF DRAWING 




®. 





i' ■" 

I 



^1 







MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 89 

2. Method of dimensioning a series of holes equally spaced 
around a circle. Note that the holes are spaced each side of 
the vertical and horizontal center Hues, and not on these center 
lines. 

Group C shows conventional uses of broken or dashed lines 

which are distinct and must not be confused with the conven- 
tional method of representing the invisible lines of an object. 
See page 76, § 54. 

(a) Shows a method of representing a moving arm when in 
its extreme positions, one position of the arm being represented 
by full Hues, the other by dashed lines. 

(b) Shows a lever in its central position and the outline 
of the lever is shown by broken lines in each' of its extreme 
positions. In designing and in bringing out certain information 
clearly it is often best to represent a part in several positions. 
In checking the drawing of an assembly of parts this method is 
effective in making sure that parts which change position do not 
interfere at any time during a complete cycle. 

(c) This shows the conventional method of representing a part 
not completely drawn, and which is adjacent to the part drawn. 

Group D shows the conventional methods of representing 
screw threads. 

(a) Shows the conventional method representing the visible 
and invisible V threads. In each case the threads begin and 
end with the short line, and in the invisible or dashed threads the 
dashes of one line are opposite the spaces of the adjacent lines. 
The short lines represent the bottom Hne of the V and should 
be of equal length; all long lines representing the top hne of 
the V should be drawn to meet the side lines. Note that the 
short Hnes in the visible thread are about twice the weight of 
the long lines. 

(b) Shows the conventional Square Thread. 

(c) Shows the conventional National Acme Thread. 

Where a part is threaded for some length it is customary to 
show only a few threads at the beginning and at the end of the 
threaded portion, thus saving time without sacrificing clearness. 
The threaded portion can be represented to scale or may be 



90 ELEMENTS OF DRAWING 

shown broken, as in the case of a shaft, etc. See Group A-i, 
§ 59, page 87. 

Group E shows the conventional method of representing a 
drilled hole, a " tapped " or threaded hole. 

1. If the hole is comparatively small a note usually states the 
size and the fact that the hole is drilled and a leader is drawn 
from the note to the place where it applies. 

2. If the hole is to be tapped a note stating the size of drill 
to be used, depth of hole, number of threads per inch and the 
form of thread is printed and a leader run to the place where the 
note applies. 

Thus, a note written if'Drl X f" X 16 U. S. tap would 
indicate that the hole is to be f '' deep and the standard tap to 
give 16 U. S. threads per inch is to be used. 

Group F shows conventional lines as ordinarily used in draw- 
ing. This subject is taken up on page 76, § 54. 

Group G shows the method of giving reference numbers. 

This subject is taken up on page 104, § 69. 

Group H shows the usual method of indicating a cross sec- 
tion of structural sheet steel, also steel shapes, such as boiler 
plate. Instead of section lines being used, the cut surface is 
made solid black. Note that in the case of several pieces being 
bolted or riveted together, they are shown slightly separated, 
since this adds to the clearness of the drawing. 

60. Drawing to Scale. Usually in making a drawing the 
object can not or need not be represented actual size, and in 
order to get the drawing on a piece of paper of convenient 
dimensions, it must be made ''to scale," that is, the actual meas- 
urements on the drawing must bear some fixed ratio to the cor- 
responding measurements on the object. The method of making 
a scale to such a ratio is to choose an arbitrary distance and let 
that distance represent one foot. This distance which represents 
one foot is then divided into twelve equal divisions, each of 
which therefore represents one inch. One of the twelve divisions 
is then divided into halves, quarters, eighths, etc. (see Fig. 31, 
page 30), to represent one-half inch, one-quarter inch, and so 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 91 

on, until such subdivisions become too small to be conveniently 
read. To illustrate, suppose a drawing is to be made one-fourth 
size. To compute the length of every line on the drawing would 
be a slow and tedious process, and would require that every 
dimension on the object be divided by 4 to get the corresponding 
dimension on the drawing. To overcome the necessity of making 
such computations, imagine an ordinary foot rule uniformly 
compressed until exactly one-fourth its original length. It would 
then be only three inches long but marked "twelve," and the 
divisions marked ''one inch" would actually be one-quarter of 
an inch long, those marked "one-half inch" would actually be 
one-eighth, etc. That is, all the dimensions would be reduced 
to one-quarter size and any desired dimension, such as 5I or gf , 
etc., could be marked off or read directly upon the drawing 
(which is one-quarter size) with this compressed rule and no 
computations whatever would he necessary. 



SCALES IN COMMON USE 


Actual Measurement on 
Drawing. 


Actual Measurement on Object 
Represented. 


Size of Drawing Compared with 
Actual Size of Object Represented. 


1 inch 


One foot 


g^th size (o.oio) 


\ inch 


One foot 


^^th size (0.021) 


1 inch t 


One foot 


a^nd size (0.031) 


5 inch 


One foot 


25th size (0.042) 


f inch t 


One foot 


t^gth size (0.063) 


I inch 


One foot 


Jjth size (0.083) 


I J inches * 


One foot 


|th size (0.125) 


3 inches * 


One foot 


^th size (0.250) 


4 inches f 


One foot 


|rd size (0.3330) 


6 inches * 


One foot 


5 size (0.500) 



* Desirable scale for ordinary use. 



t Rarely used. 



The above table should be thoroughly understood as beginners 
are often misled by the way the instrument is marked. 

For example, the "J" marked on the instrument does not indi- 
cate that this scale is for making a drawing \ size, but that \ inch 



92 ELEMENTS OF DRAWING 

has been divided to represent some convenient division of inches 
in one foot. This scale of J inch to the foot is 12" -r- j" = ^^ 
full size, while the | size would be 12" X i = 3", or a scale of 3" 
to the foot. Another fact to remember is that dimension 
numbers which the draftsman prints on the drawing are the 
actual dimensions as measured on the object represented, and 
not the distance obtained by measurement on the drawing with 
the ordinary foot rule unless the drawing happens to be full size. 

The scales most used in practice are full size, or 12 inches 
equals i foot; one-half size, or 6 inches equals i foot; one-fourth 
size, or 3 inches equals i foot, and one-eighth size, or i| inches 
equals i foot. If an object is very small the scale of the draw- 
ing may be increased in order to make a satisfactory drawing. 
For example, twice size would mean 12 inches on the drawing 
represents 6 inches on the object. It is often useful to be able 
to read these scales directly from the foot rule and not be depend- 
ent upon the special graduation. This is easily done by remem- 
bering that for a scale of 6 inches to the foot, i inch will 
be represented on the scale by | inch, and reading each | inch as 
I inch, the subdivisions of the foot rule would read as follows: 
I" on the drawing = i" on the object, |" = |", tV" = i", etc. 

For 3 inches to the foot, or J size, i inch is represented by 
J inch, and the subdivisions would be read thus : f " = |'', 

For i| inches to the foot, or | size, i inch is represented by 
^ inch, and the subdivisions are read thus : tV" = |", sV = 4", etc. 

Sometimes an unusual 
scale is required, such as a 
shrink rule for pattern 
makers. To construct such 
a scale or rule, secure a 
Fig. 66. -Shrink Rule. standard twelve-inch rule 

and the blank rule that is to represent twelve inches on the new 
scale, as shown in Fig. 66. Make a ruling gauge, G, of thin sheet 
metal, with a guide flange turned down to bear against the 
outer edge of the blank. Slide the gauge along the blank and 
mark the graduations as the upper edge of the gauge coincides 
with the standard graduations. 





7£2\.uifLA.fL.d\.ud 


*l .9|/ 

.l,l,l,l,l,l,lll/!j.;r 


,i,l,i,l,i,I7i, 


<s> 




-~~j^ 


^TTTTrrr.^ ! 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 93 



61. Choice of Scale in Drawing. The best scales to use in 
making shop drawings are full size, half size, three inches to the 
foot, and one and one-half inches to the foot. The one used 
depends on the relative proportion of the size of the object 
and the size of the drawing desired. The scale of a drawing 
should not be so small that all dimensions and information 
cannot be clearly given. After the scale of a drawing has been 
decided upon, it must be rigidly adhered to throughout the 
construction of the views of a single part, but different parts 
may be drawn to different scales if there is any advantage to 
be gained in so doing. 

To illustrate how to determine the largest scale that can be 
used for any particular drawing, suppose a drawing of the Lathe 
Leg (see page 122, Fig. 84) 
is to be made on a stand- 
ard 12" X 18" sheet and 
is to consist of three views. 
A rough sketch as shown in 
Fig. 67 is made to some 
scale, and the size of the 
rectangle required to in- 
close the necessary views, 
when grouped in their 
proper relation to one an- 
other, is determined. This 
rectangle measures 42" by 
36", and therefore if 
drawn one-half size it 

would be (I of 42 = 21 by ^'S- 67. —Determining the Scale. 

§ of 36 = 18) 21" by 18", and could not be drawn on the sheet 
which has a working space of only ,16" by 11" (see page 106, 
Fig. 73). The largest scale possible, if the part is represented 
vertically on the sheet, will next be determined. Dividing 11 
by 42" gives approximately 0.26, and, referring to § 60, page 91, 
it is seen that the nearest desirable scale corresponding to 0.26 
is I size, or 3" = i foot. This scale is therefore adopted, 
the drawing is arranged vertically on the sheet, and the balance 
of the space is available for other purposes. 




94 ELEMENTS OF DRAWING 

When it is desired to represent a number of parts on a single 
sheet of fixed size, each part should be handled as described 
above. After the scale has been decided on, the rectangles 
should be laid out very lightly on the sheet and arranged sym- 
metrically before beginning the actual work of drawing, care 
being taken that views are separated by sufficient space to prop- 
erly allow for all dimensions. 

62. Dimensioning Working Drawings. The dimensions are 
the most important feature of the drawing, and so far as the 
workman is concerned the drawing serves only to show where 
the dimensions apply. 

To be of use the dimensioning must be done systematically, 
and with the needs of those who will use the drawing constantly 
in mind. The proper dimensions are determined by considering 
the processes the material must undergo in the making of the 
part. In considering such processes the methods and available 
tools of the different departments of the shop through which 
the part will pass to reach the finished state must be kept in 
mind, and those dimensions given which the workmen will 
require. 

A drawing has been completely dimensioned when it has all 
information necessary for getting out stock, making patterns 
and cores, machining, erecting, etc., the information being in 
such shape that no workman will be required to make a compu- 
tation to get a necessary dimension, or to seek information of 
any kind beyond that recorded on the drawing or specifications. 

The ability to dimension a drawing satisfactorily comes from 
experience and a thorough knowledge of the shop processes used 
in making each part. A few general requirements, however, 
can be given, and these should be carefully studied by the 
beginner before attempting to dimension a drawing. 

The dimensions on a drawing must be accurate, useful, clear, 
and complete. If the dimensioning is inaccurate, no degree of 
perfection otherwise can redeem the drawing; it is worse than 
useless, for when the part the drawing represents is made it will 
be wrong, and the labor and, depending on the magnitude of 
the error, material will be totally or partially lost. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 95 

To lessen chances of making an error, check computed dimen- 
sions by scaling and scaled dimensions by computation, and if 
the two do not agree determine which is wrong. Always bear 
in mind that the dimension figures on a drawing represent the 
actual measurements on the object, and not the measurements 
on the drawing, so that in case the " scaled ^^ dimensions and the 
calculated dimensions fail to agree, the workman will assume that 
the figures are correct and make the part accordingly. 

K a dimension is not to scale, however, indicate the fact in 
some manner. This is sometimes done by underlining these 
figures which are not to scale. 

Place arrowheads so no mistake can be made as to where the 
dimension applies. There must never be the least doubt in 
this regard, and the dimension line must always he drawn far 
enough from other lines to avoid confusion. The dimension 
numbers must be perfectly plain and placed as near the center 
of the dimension line as practicable, and they should read from 
the bottom or right-hand side of the drawing. Never place di- 
mension numbers on center lines and never draw a line of any 
kind through such numbers. 

The numbers expressing a dimension should be so selected 
that they can be conveniently used by the workmen — - feet, inches, 
fractions, or decimals, as the case may be. Because of the 
general use made of the two-foot rule, dimension figures up to 
24 inches should be expressed in inches; from and including 24 
inches they should be expressed in feet and inches. 

To avoid chance of mistakes the abbreviation Ft. should be 
written after the number of feet, and the double accent mark 
used to indicate inches. The numbers representing feet and 
representing inches are separated by a dash one-eighth of an 
inch long, thus 18 Ft. - 7". 

In some classes of work, such as locomotive work, dimensions 
are often given in inches only. 

Judgment must he used in the degree of refinement called for by the 
dimension. Rough castings, even if small, cannot be measured 
to one-sixteenth of an inch accurately, and therefore it is useless 
to give a precise measurement between a finished surface and 
the end of a casting, while in the case of such work as a force fit 



96 ELEMENTS OF DRAWING 

the dimension may be given to several decimal places, the vari- 
ation allowable from the given figure being indicated in the 
following manner: 3-128 lli°;°°^ , — meaning that a variation of 
0.005 above or below 3.128 is permissible. 

Where dimensions on the drawing indicate the final dimen- 
sions of the part when complete, no allowances are made by 
the draftsman for shrinkage of castings, finishing, etc., as this is 
usually taken care of in the shop. 

The over-alLdimensions are so frequently useful in estimating, 
getting out stock, etc., that they should always be given. Place 
over-all dimensions outside of subdimensions, and in cases where 
dimensions are grouped in parallel lines the shortest dimension 
should be inside, the longest outside, and all others so arranged 
that dimension lines do not cross. 

Always check over-all dimensions carefully to see that they 
agree with the sum of the dimensions which go to make them up. 
Do not rely upon scaling alone in adding up a line of subdi- 
mensions to determine an over-all dimension, because if the 
drawing is slightly out of scale the result w^ll be wrong. 

If a subdivided dimension is between a finished surface and 
the end of a casting, the last subdivided dimension should be 
omitted and an over-all dimension given. 

The inexperienced draftsman will often give dimensions on 
a drawing which it is impossible for the workman to use in 
making the part. For this reason the dimensions placed on a 
drawing in a haphazard way, even if accurate, are very often 
worse than useless. All- measurements possible should be from 
center lines that are convenient for the workman to locate on the 
object or from finished surfaces. Give the distance between 
centers of important parts, and if the object is symmet- 
rical, give the distance of these centers from the main center 
line. 

Do not repeat dimensions unnecessarily as this increases the 
possibility of error. Where it is necessary to repeat dimensions 
an error is more likely to be discovered if the dimensions are 
placed in corresponding positions on the different views. 

Similar parts should be similarly dimensioned and dimensions 
which are related should be kept near one another. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 97 

Do not crowd all dimensions on a single view, but distribute 
them to avoid confusion. 

Dimensions should not be crowded into limits inadequate to 
receive them, and if the space is too small for the figures, they 
may be placed outside, with or without a leader — that is, a 
line drawn to indicate where a note or dimension applies (see 
Fig. 88, page 125). 

If the space between reference lines is too small to receive well- 
formed arrowheads, the arrowheads may be reversed and placed 
outside of the space to be dimensioned, see Fig. 82, page 118. 
When a dimension falls on a section,ed area, the section lining 
is omitted at the place where the dimension numbers are given. 

Where a complete circle is shown on the drawing, such as 
a bored hole or turned piece, give the diameter. Cored holes 
are dimensioned by giving the diameter and stating that they 
are to be cored; thus, |"core. Fillets and rounded corners are 
given by their radii. In giving the radius of a circle, R or Rad. 
is written after the dimension figures, and an arrowhead is 
placed at the arc but not at the center. Threaded pieces and 
tapped holes are dimensioned by giving the diameter and num- 
ber of threads per inch; thus, |'-i3 thd., or i"-i3 tap. 

Dimensions of angles should be given in degrees and minutes 
or by coordina tes from a reference line, depending on how they 
are to be used. Tapers should be stated per foot of length 
and in the case of conical surfaces should be given as taper on 
the diameter. 

63. Notes on a Drawing. Lengthy notes should not be re- 
quired on a drawing to make it clear, but there are times when 
the art of drawing fails in its purpose and a brief note carefully 
worded saves the workman much uncertainty. In such cases 
an explicit note of instruction is not only permissible. but abso- 
lutely essential. When possible, notes should be placed in hori- 
zontal lines and very close to the part to which they refer, in order 
that they may be quickly read and easily understood. All notes 
should consist of short, explicit and concise sentences, should 
leave no doubt as to their exact meaning, and should read from 
the bottom or the right-hand side of the drawing. 



98 ELEMENTS OF DRAWING 

State all special directions and instructions pertaining to 
making, painting, shipping,- erecting, etc., in properly worded 
notes. No lettering of notes should be attempted on the draw- 
ing without first ruling very light guide lines to insure an even 
height and slope of letters. Guide lines should be drawn very 
lightly and erased after the note is completed. Retrace any 
letters made dim by erasing. All notes on drawings in this 
course must be lettered in the standard Gothic capitals, unless 
otherwise stated. The letters must be -3^" high. Figures in a 
note should be made slightly higher than the letters, say, |" high. 

64. Indicating the Finish of Surfaces. The surfaces of a 
casting or forging are spoken of as " rough " when in the condi- 
tion in which they leave the foundry or mill, and "finished" 
when the piece has been subjected to some tool operation. 
Some of the shop operations for finishing surfaces with cutting 
tools are turning, planing, milling, grinding, reaming, filing, 
scraping, and chipping; besides these processes, surfaces are 
often polished, grained, matted, etc., to produce artistic effects. 
It is necessary to indicate on the drawing the kind of finish a 
surface is to be given, so that the proper department will attend 
to it, and also in order that the pattern maker or blacksmith 
will allow for the material that must be removed in producing 
this finish. The usual method of indicating a finish made by 
machining is to place the letter / across the edge view of the 
surface to be so finished. (See Fig. 68.) If it is 
f -j to be other than the ordinary machine finish, a 
V note to that effect should be added and a leader 



^ run from the note to the finish mark. If all the 

Fig. 68. —Method 

of indicating ordi- surfacc of a part is to be finished the several "/" 
a surfa^e"!^'^" ""^ ^^^^^ ^^^ Omitted and the note "f ALL OVER'' 
is printed near the part number. As shop methods 
and processes are continually being changed in an effort to 
increase production and reduce the cost of manufacture the 
drawing should not specify* the process by which the finish is 
to be obtained. 

65. Use of Record Forms and Titles. A complete record 
must be kept of every drawing, and most of this record should 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 99 

be on the drawing itself in a particular and invariable space re- 
served for that purpose. That portion of the record which is 
placed on the drawing should be systematically tabulated accord- 
ing to a fixed form and should embrace at least the following items : 

(i) An appropriate title which will adequately describe the con- 
tents of the drawing. 

(2) The name and address of the firm for which the drawing 
is made. 

(3) The title and names or initials of those who are responsible 
for the finished drawing; this includes at least the checker and 
the approving engineer. 

(4) The drawing number and a " part number " where necessary. 

(5) A record of all changes made in the drawing to adjust it to 
meet conditions other than those for which it was originally intended. 

(6) The date the drawing is officially adopted. 

(7) The size of the drawing should be indicated in some manner 
so that it can be properly and systematically filed. 

Besides the above information some companies insist that the 
drawing bear the name and initial of all those responsible for it 
in any way. If this burdens the drawing with information use- 
ful in the drawing department only, the complete history of the 
drawing can be recorded on cards or in a special book reserved 
for that purpose. Also the machine or apparatus for which a 
part is usually first designed is recorded and some scheme is 
adopted such that if a part is used on several different machines 
the fact is recorded in such a manner that unnecessary dupli- 
cation of patterns or uncertainty as to the number of pieces to 
be kept in stock is avoided. 

It is very common practice to indicate the " scale " to which 
the parts represented on a drawing have been made, but the 
value of this practice is questionable, as there is a rule almost 
universally appHed that "the workman must not scale a draw- 
ing to obtain a dimension." Also during the life of a drawing 
it frequently happens that dimensions are changed, but the 
drawing is not "kept to scale"; and for these reasons the 
"scale" on a drawing might be a temptation to break 
the above rule and in addition be misleading. 



lOO ELEMENTS OF DRAWING 

In practice many different systems are used to keep a record 
of changes on a drawing, the purpose being to have a history 
of progress made, and to be able to furnish repair parts for 
machines in service. There are several features to be taken 
care of in this connection but it is not within the scope of this 
book to go beyond pointing out the necessity of keeping a 
thoroughly reliable history of changes made during the life of a 
drawing. 

66. The Title-form on a Drawing. The best location for a 
title-form is the lower right-hand corner of the sheet. This 
information so placed makes it easy to handle and file the 
drawing and particularly tracings. 

There is no accepted standard for the outline and dimensions 
of a title-form, or the information recorded, but each individual 
establishment evolves one that is suited to its own use. Care 
should be taken in the final selection of a title-form as it is a 
very important item in a drawing room system. 

The title-form shown in Fig. 69 represents a genera,! average, 
and will be used in this work on all mechanical drawings of the 



Print Title Here. 



^ZZMACHINE DESIGN 

"q/BLEy COLLEGE 



'-fZ'ITHACA, NEW YORK '^no 



irT±- 



DRA WN ^Kl"3*o 

INSRECTED_1_ . 

DATEAPRV'D 



'JDRAWING-C 101 



Kite 



5(0 



iQib 



Fig. 69. — Title-form to be used in this Work. 

12" X 18" size. This title-form, while especially applied to 
this work, follows closely the one now used successfully by 
several large manufacturing concerns. 

All the lettering in the title-form is the .Capital Slant Gothic 
style. By using the method described on page 69, §49, the 
lettering in the title can be more satisfactorily arranged by the 
beginner. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE lOI 

The lettering of the title (or name of the drawing) is ts" 
high, and is located " centrally " in the space provided for that 
purpose which is if" X 5I". 

All other lettering in the title-form is |" high except the 
words DRAWING and SIBLEY COLLEGE (or whatever the 
name of the institution), which are fV" high. 

The space between all lines of lettering in the title-form is 
tV" on the right-hand side and |" on the left-hand side. 



67. Bill of Material. A bill of material should be placed on 
every detail drawing to give the information required to make 
up the orders for the pattern shop, foundry, machine and forge 





J" 

4 


-s — 


-f^ 


"^ s ^ 


"* 4 '' 


1" 
4 










"^ 2^ 


"^ 


"^ 


























^ 






















.^ 


















m|"o 


^^ 


. 












t 


























\ 


















■4 
















Q 


03 








^BORDERLINE 











^^EDCE OF SHEET 

Fig. 70. — Bill of Material Form used in this Work. 

shops; to get out machine lists, figure stock, cost, etc. The 
form for tabulating this data varies with different companies, as 
does also the place it occupies on the drawing. Fig. 70 shows 
a form for the bill of material that has proven entirely satisfac- 
tory under severe conditions and will be adopted for this work. 
In Fig. 70 the space if" X sf " directly in the corner is reserved 
for the title-form (see page 100, § 66). Unless otherwise stated, 
locate the bill of material form just above the title-form, and 
provide at least as many ^ig" spaces as there are parts detailed 
and standard parts called for on the drawing. In practice 
extra t\'- spaces are drawn to provide for future addition of 
parts. 



I02 ELEMENTS OF DRAWING 

All lettering in the bill of material is -i^" high, is of the slant 
Gothic style, and is preferably all capitals. 

The first column on the left contains the number of pieces 
required to make one complete machine (or structure) — in this 
case one lathe. The second column contains information as to 
the material of which the part is to be made. The third column 
is for cross reference and refers to patterns, other drawings, 
punches, dies, etc., and conveys some special information or 
instruction which is required to make the data in column four 
complete. Thus, if the bill of material on one drawing called for 
a piece, say, a washer, exactly the same as had been previously 
detailed on another drawing for a different machine, then column 
three would contain the word " punching," which explains how 
the part is made, and in column four would be written,'' C-171," 
which would be the size and number of the drawing on which the 
washer is detailed. Should a part require the use of a pattern 
which has already been made for another machine, that fact 
could be recorded by writing in column three the abbreviation 
" Patt." for pattern, and the number of the pattern would be 
printed in column four. The fourth column contains pattern 
numbers (see page 104, § 70) when the part is a casting, punch 
and die numbers when the part is a punching, etc., and for 
other classes of work may be used as indicated above. The 
fifth column contains the part numbers. See page, 104, § 69. 
The sixth column contains the name of the part and any other 
information thought necessary to identify the part. 

This particular form of a bill of material has distinctive and 
valuable features which should be understood. It is so laid out 
that the part numbers, pattern letters, etc., read from the bottom 
upward; this is done in order that a new part number may be 
added at any time. Also it is often found necessary to make a 
machine differing very little from one already detailed, and ad- 
ditional columns, each of which is exactly the same width -as 
column one (see page 119, Fig. 83), can be added to the left of 
column one and new groups made. To illustrate, suppose a 
firm manufacturing the speed lathe should receive an order 
for a lathe of the same general design as the standard machine 
but to have a bed six inches longer. All that is necessary under 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 1 03 

this system is to make out a new list to the left of column one 
and call it group two; schedule all parts in this group as in 
group one except the bed; add another part number to the top 
of the bill of material, and schedule the longer bed. Then add 
a note near the drawing of the original bed stating that for 
group 2 the- bed is to be a certain length, and the drawings 
would be ready to go through the shop on the new order. 

Wherever possible, parts which fit together on the complete 
machine should be recorded in the bill of material as consecutive 
items, as this simplifies checking and erecting. For example, if 
two castings fit together and are given the part numbers i and 
2, the bolts or screws for fastening them together should be 
number 3. 

When standard parts are required, such as standard bolts, 
nuts, washers, screws, etc., they are not detailed on the drawing, 
but are given a part number, and this number is printed in the 
regular way close to the place where the part is to fit, and an 
arrow from the circle points to the exact place it is used. This 
part number is also printed in the bill of material. 

The name of the material is usually abbreviated in the bill 
of material, some of the more common abbreviations being 
Cast Iron, C.I.; Wrought Iron, W.I.; Malleable Iron, MalJ. 
Machine Steel, M.S.; Cold Rolled Steel, C.R.S.; Cast Steel, C.S. 
Steel Forging, S. Forg.; Steel Tubing, S. Tube.; Brass, B. 
Bronze, Bz.; Phosphor Bronze, Ph. Bz.; Copper, Cop.; Babbitt, 
Bbt. ; Fiber, Fbr. Where it is necessary to use a material of an 
exact analysis or specification it is best to call for it by a number 
(see page 81, § 55). 

68. Numbering and Indicating the Size of Drawings. In 
order to be easily classified, recorded, filed, and referred to, draw- 
ings should be given a number. There is no universally accepted 
system for numbering drawings, and the method followed by 
each particular firm depends largely on the magnitude and 
variety of its business. 

It is also necessary to have some simple and effective means 
of indicating the size of a drawing, as those of different sizes are 
usually filed in different cases or drawers. 



I04 ELEMENTS OF DRAWING 

In order to secure uniformity, and also to save waste in cutting 
paper and tracing cloth, four standard sizes of drawings have 
been adopted in most commercial drawing rooms, and these 
sizes are indicated on the drawing by a capital letter used in 
connection with the number of the drawing. For instance, the 
sizes indicated by the letter might be as follows : The letter A 
to indicate a drawing 24" X 36"; B, a drawing 18" X 24"; C, a 
drawing 12" X 18"; D, a drawing 9" X 12". 

In this course all exercises in mechanical drawing are worked 
on paper 12" X 18", and consequently their size is indicated by 
the capital letter C, and the block of numbers reserved for 
this work begins with loi and extends to 200. Thus drawing 
C-103 would be 12" X 18" in size, and the third consecutive 
mechanical drawing made in the course. 

69. Part Numbers on a Drawing. In order to refer to any 
individual part (or element of a machine) in making up orders, 
tabulating bills of material, etc., each part detailed on a drawing 
is given a number to identify it. This identifying number is 
termed the "part number" (or reference number), ^nd is printed 
near the views of the part and is inclosed in a circle. On a 
pencil drawing both number and circle 
are double lined, but these are drawn5,j<»| 
solid when inked. (See Fig. 71.) The . 
circle should always be drawn after Fig. 71. —Layout of "Part 
the number is formed and iji such a Numbers » as used m this work. 

position that the number appears "central" in the circle. 

It sometimes happens that a single part will require more 
than one part number. As an example, take the washer detailed 
on drawing C-ioi. Two washers are required, of exactly the 
same form and dimensions, but are made of different materials. 
Therefore, in place of repeating the drawing of the washer, the 
one drawing is given two numbers, and the material of which 
each is made is called for at the proper place in the bill of 
material. 

70. Recording Patterns on a Drawing. When a pattern is 
required in order to produce a part, the pattern should be given 




MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 105 

a number so that it can be listed, identified and referred to. 
This n'umber is usually assigned in the drawing room and is re- 
corded in the bill of materials. This will be explained more 
fully later. When practical these numbers are fastened to the 
pattern in raised figures and letters, and therefore appear on 
the casting. By this means a broken or obsolete part of a 
machine may be replaced by simply ordering the part by its 
number from the manufacturers. 

The method to be followed in this course for marking pat- 
terns will be to give to them the same number as the drawing on 
which the part is first detailed, and then add a capital letter to 
identify the patterns required by the different parts detailed on 
a single sheet. The pattern letters on each drawing begin with A 
and continue through the alphabet in the order they are recorded 
in the bill of material. Thus, the first pattern required on 
drawing 158 would be marked '' Patt. 158-A"; the second 
would be marked " Patt. 158-B," and so on through the alpha- 
bet as far as necessary. It often occurs that in a new machine 
some part requiring a pattern will be the same as the corre- 
sponding part of an old machine. In such cases the old pattern 
number must he given on the new drawing, and the old pattern 
used for the new machine. For example, suppose the fourth 
pattern required on drawing 136 could be used for the first 
pattern required by drawing 158. Instead of numbering 
the pattern 158-A, it would keep its old number (136-D) and 
would be recorded as 136-D on drawing 158. The lettering 
of the new patterns required on drawing 158 would not be 
affected by the fact that one or more old patterns are called 
for. In marking patterns, such letters as /, O, and Q should 
be avoided, as they are easily confused with numerals of 
similar outline. 

71. Time Keeping in Drawing. In practice the draftsman is 
usually required to keep a record of the time devoted to each 
drawing. This record is usually kept in a time book or on cards, 
and is of value in computing drawing-room expenses, as well 
as useful in determining to some extent the value of the drafts- 
man's services to the company. 



io6 



ELEMENTS OF DRAWING 



FINISHED. 



TOTAL HOURS- 



DESK NO. . 



Fig. 72. — Time-keeping Form 
used in this Work. 



In order to apply the principle of 
time-keeping in this course and yet 
avoid using the card system the form 
as shown in Fig. 72 will be used. 
This form is to be printed with the 
rubber stamp (provided for the pur- 
pose) just above the lower border 
line, and to the left of the title-form, 
unless another location is indicated. 



72. Border Lines. Border lines are drawn parallel to and 
near the edges of the paper to form a frame for the drawing. 



EDGE OF PAPER- 



4- 



«- 



-18^ 



CM 



BORDER LINE — 5> 



-16^ 



-BORDER LIJJJE 



□ 



-5f 



n\-. 



T 



/^j 



EDGE OF PAPER-^ 

Fig. 73. — Layout of Standard Drawing as used in this Work. 

Their principal object is to set off a margin, which gives the 
drawing a finished appearance, and to lessen the chances of poor 
results in trimming and blue printing. The border lines should 
be drawn very close, say, | inch from the edge of the paper, as this 
margin represents so much waste space. The border lines should 
be the first lines drawn on a pencil drawing, in order to act as match 
lines to reset the drawing in case it has to be temporarily re- 
moved or shifted. The border lines are drawn in last on an inked 
drawing and should not be too heavy, say, not over ^V" wide, the 
exact width depending somewhat on the size of the drawing. 

Fig. 73 shows the layout of border line to be used in this 
work. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 107 

Having placed the paper " square " on the board (see this 
page, §73), draw a very light horizontal line entirely across 
the paper, f" from the top edge; make a mark on this line 
I" from the right-hand edge of the paper, and then with the 
aid of the triangle, guided by the working edge of the T- 
square blade, draw in very lightly the right-hand vertical line 
through this point. Next, lay off the distance between the 
right and left hand border lines along the top border line, and 
by aid of the T-square and the triangle draw in the left-hand 
border line. On this line lay off the distance between the top 
and bottom border lines, and with the T-square draw in the 
bottom border line. Any part of the lines extending beyond 
the corners must he erased, and ihe whole border retraced and 
the lines made clear cut and of the desired weight. The wide 
margin on the left is to allow for binding the sheets of this 
course together. In practice, however, it is customary to have 
the same margin on all sides. 

73. To Fasten the Paper or Tracing Cloth to the Board. The 

paper or cloth should be "square" with the board; it should lie 
perfectly flat and smooth, and only one drawing should be tacked 




Fig. 74. — Placing a Drawing on the Board. 

on the board at a time. Place the paper about midway between 
top and bottom, and rather close to the left-hand edge (i.e., 
working edge) of the drawing board and insert a thumb tack 
in the upper left-hand corner. Then, holding the T-square in 
its proper position with the left hand, manipulate the paper or 
cloth with the right hand until the upper edge of the paper and 
the working edge of the T-square are in line. (See Fig. 74.) 
Smooth the paper diagonally with the right hand from the 
upper left-hand to the lower right-hand corner and tack this 



io8 ELEMENTS OF DRAWING 

corner down. Next,, smooth the paper from the center to each 
of the other two corners and tack them down. To securely 
fasten large sheets, it is usually necessary to use thumb tacks 
along the edges as well as at each corner of the sheet. All 
thumb tacks should be so placed that the outer edge of the 
head comes about even with the edge of the drawing paper or 
tracing cloth. Also the thumb-tack head must be pushed tight 
against the paper so that the head will offer the least obstruc- 
tion to the triangles and T-square. It is often advisable in 
doing accurate work to temporarily remove a thumb tack if the 
head interferes with the free use of triangles or T-square, but 
in such cases the alignment of the drawing must not be dis- 
turbed. 

Stretching or smoothing the paper or tracing-cloth with soiled 
or moist hands injures the drawing surface. 

Unless stated to the contrary, the drawing paper for this 
course should he tacked down with short dimensions parallel to the 
working edge of the drawing hoard. 

74. To make a Pencil Drawing. Good penciling is a requi- 
site to good, inking, and a drawing is seldom improved in inking 
if poorly done in pencil. The pencil must be kept well sharp- 
ened (see page 15, § 14), so that the lines drawn will be clear, 
sharp, and of the proper weight. 

The direction in which mechanically made lines in either 
pencil or ink should be drawn is shown on page 21, Fig. 19. 
Vertical lines and all those lying in the angle AOC are ruled 
against the left-hand edge of the triangle and the lines in the 
angle COE are ruled against the right-hand edge. 

Center lines should first be drawn as light continuous lines, 
and later be retraced in their proper construction, being left 
broken where necessary to avoid crossing a dimension figure. 
Such a break in a center line should be made about the middle 
of a long dash and should not immediately precede or follow a 
short dash of the line. If the center lines are drawn heavy at 
first they must be erased at the places where they would cross 
dimensions, and if not gone over again the ends next to where 
the erasing was done are ragged. 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 109 

Do not complete each view separately, but, having one well 
along, commence the drawing of others. In this manner errors 
are more readily detected, and the drawing of each view be- 
comes a check on the others. All the views, however, repre- 
senting one part should be completed before starting to draw 
another part on the same sheet. 

In making drawings of spindles, shafts, and parts where most 
of the lines are at right angles to one another, measure off the 
horizontal lengths along the center line, and through these 
points draw the vertical lines of the drawing very lightly and of 
indefinite length. On these vertical lines measure the diameters, 
and through these points draw in the horizontal lines. These 
may be put in full weight at once, since their limits are defined 
by the light vertical lines. Next, that portion of the light ver- 
tical line which is needed is drawn in heavy. All the Kghtly 
drawn horizontal Hnes which are to become dimension Hnes are 
next gone over (between the proper reference lines) and formed 
into the two short and one long dash construction. These lines 
should be made of the proper weight, and left properly broken 
for their dimension figures. When all of the dimension lines 
are on the drawing, put in the arrowheads and dimensions, then 
letter in the necessary notes. Do not print in the dimension 
numbers until the drawing is completed, as this insures greater 
accuracy. There should be a space of at least tf" between a 
note and any line of the drawing, including dimension lines and 
figures. In laying off dimensions, point them off directly from 
the scale (see page 30, Fig. 32), and do not transfer them from 
the scale to the drawing by use of the dividers. 

Time is often gained and the work is usually more accurate 
if the drawing is systematically done. A good method of pro- 
cedure in making a pencil drawing is as follows : 

1. Draw border lines. 

2. Block out hill of material and title form. 

3. Arrange the views (see page 74, Figs. 50 and 51, also 
page 75, Fig. 52) and draw main center lines. 

4. Draw the main lines of the part, using very light continuous 
lines. 

5. Complete all views of the part. 



110 ELEMENTS OF DRAWING 

6. Put in dimensions and notes. 

7. Retrace center lines j making them the proper weight and oj 
the characteristic dot and dash construction. 

8. Complete title and hill of material. 

75. Inking Drawings. Before beginning to ink, thoroughly 
clean the drawing, removing all dust, lint, particles of worn- 
off rubber, etc., and be exceedingly careful that the hands and 
instruments, especially the triangles and the T-square, are clean 
and free from dust, so that they will not soil the drawing. 

Examine the points of the bow pen, compass, or ordinary 
pen before using them, to make sure that the nibs are clean, 
are of the same length, and come together evenly. Always 
shake the ink bottle well before using the ink, since, when the 
bottle stands undisturbed for some time, the coloring matter 
in the ink gradually settles to the bottom. Under such con- 
ditions the charge of ink carried by the pen will not be of the 
same density, but will be more highly colored at first, and as the 
thinner ink from above reaches the drawing surface the line will 
vary in color; that is, taking the case of black ink, it will vary 
from a jet black to a grayish black in appearance. When such 
lines are on tracings it is impossible to obtain satisfactory blue- 
prints. After filling the instrument with ink, test it on a sepa- 
rate piece of paper to see that the ink is flowing properly and 
that the width of the line is correct. If the ink does not flow 
freely, touch the point of the pen to the drawing board, the 
penwiper, or the end of the finger. If ink still does not flow, 

slightly dampen the finger and touch 
it to the point of the pen, or remove 
the dried ink with a slip of thin paper 
drawn between the nibs. (See Fig. 
7S.) As a last resort, thoroughly 

Fig. 75. — Cleaning the Ruling Pen. \^ 1 ,-,i , 

clean and refill the pen. More un- 
satisfactory work results from the use of a dirty pen than from any 
other cause, hence the nibs of the pen should he cleaned each time 
a charge of ink has been exhausted, and under no circumstances 
should the pen he put away without having heen first thoroughly 
cleaned. 




MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE ill 

Before inking a line, understand what kind of a line it is, 
that is, whether full or broken, the purpose of the line, and 
where it begins and ends. Start inking at the top and left-hand 
side, and work down and toward the right, for in this way the 
wet ink is not smeared with the hand, T-square, or triangles. 

In drawing a line, hold the pen at the starting point for an 
instant until the ink begins to flow, and then move it along the 
pencil line at a uniform and moderate speed. On reaching the 
end of the line, immediately raise the pen from the drawing, 
otherwise the ink continues to flow and the line spreads at the 
end. If a good line is not produced at the first attempt, do not 
push the pen backward over the line, but go over it a second time 
in the proper direction, taking care not to widen the line in 
retracing. If several lines meet at a point, allow sufficient time 
for each line in turn to dry, and, if possible, ink from, and not 
toward, the point of intersection. Since it is difficult for a be- 
ginner to join two lines so that they appear smooth and contin- 
uous, the pen should hold sufficient ink at the beginning to complete 
the line. Too much ink in the pen gives a heavier line than 
is desired, and too little ink results in too light a line. 

Blotting and faulty lines are two of the main sources of trouble 
in inking a drawing. Blotting may result from overloading the 
pen with ink; from allowing the ruling edge to come in contact 
with a line before it is dry; from lint, particles of worn-off 
rubber, or dust being caught on the point of the pen; from 
inclining the pen toward the ruling edge so that ink is drawn 
under the edge of the T-square or triangle; from getting ink on 
the outside of the nibs in filling the pen, or because of the nibs 
being nicked, corroded, or otherwise out of condition. If a blot 
is made, absorb the surplus ink by applying the corner of a 
blotter to the top of the ink globule. To lay the blotting paper 
directly on the blot tends to spread the ink and to injure the 
wet surface. 

Faulty lines are usually of variable width or ragged along the 
edges. A line of variable width may result from changing the 
speed at which the pen is moved, thus causing a variable flow 
of ink; and from varying the pressure against the drawing 
or ruling edge, thus springmg the blades and changing the dis- 



112 ELEMENTS OF DRAWING 

tance between the nibs. The pen point may encounter lint, dust, 
or particles of worn-off rubber in its path, thus causing the 
ink to flow irregularly, or the pen may be too full or not suffi- 
ciently full of ink, thus varying the rate of ink flow. 

A ragged line may result from the pen not being clean; the 
nibs being so dull that the edges of the line are broken ; both nibs 
not touching the drawing at the same time, due either to the 
blades being of different length or because the pen is not held 
in a vertical plane parallel to the working edge. 

Always allow ink to become thoroughly dry before attempting to 
erase it. 

Drawing ink should never be blotted as this causes the lines 
to appear dim and blotting on a tracing destroys the opaque 
qualities of the line for printing. A very wide line should be 
" built up " of a series of narrower merging lines made by par- 
allel strokes. 
Do not place the ink bottle on the drawing board as ink 

may be accidentally 

spilled. The danger of 

overturning may be 

lessened by using an ink 

bottle holder, sev- 

eral styles of 

which are on the 

market. A circu- 

,,„.„_ lar piece of wood 

Fig. 76. — Two Simple Designs of Ink Bottle Holders. '- 

or a piece of draw- 
ing paper cut to receive the bottle and hold it securely, as shown 
in Fig. 76, is commonly used. 

The drawing, when not in use, should be kept covered with 
an extra piece of paper to protect it from the dust and dirt. . 

Never begin inking a drawing until it has been completely 
finished in pencil; and, in order to get the best results and to 
save time, do the inking systematically. Opinions differ as to 
the best order of inking the lines on a drawing, but on one 
point all are practically agreed, namely, that curves tangent to or 
joining straight lines should be inked first, and the straight lines 
drawn to the curves. 




MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 113 

In inking, a very good method of procedure is as follows : 

(i) circles and arcs, beginning with the smallest; 

(2) outlines, beginning with the lightest and inking all of one 
weight before taking up the next heavier; 

(3) hidden surface lines; 

(4) extension lines and dimension lines; 

(5) arrowheads, dimensions and notes; 

(6) cross-section lines; 

(7) bill of material and title; 

(8) border lines. 

76. Checking Drawings. The process of checking consists in 
making a thorough examination of every detail and feature of 
the drawing to detect any errors it may contain. The impor- 
tance of efficient checking is reahzed when the ease with which 
an error can be corrected on a drawing is compared with the 
difficulties and expense that would result if the same changes 
had to be made on a pattern, casting, or forging. Final check- 
ing should not be done by the same draftsman who made the 
drawing, as one does not readily detect his own errors. In 
most drawing rooms there is an official " checker " whose duty 
it is to see that drawings are correct in every detail and who is 
responsible for the Lccuracy of drawings which bear the official 
mark to indicate they have been checked. The checker usually 
signs his initials and the date of checking in the title form of 
the drawing. 

The beginner should always check his own work thoroughly in 
order to gain some knowledge of checking, as well as to detect 
any oversights or errors it may contain. The checker must first 
inform himself of what is wanted, and then by methodical steps 
examine the drawing to see if it completely fulffils all require- 
ments. A good method of procedure in checking is as follows: 

1. See that a drawing of every part and of necessary assem- 
blies has been made, and that enough views are correctly drawn to 
completely represent each part. ■ ^ j 

2. See that all scale dimensions agree with the dimension 
figures given on the drawing, and that where a series of sub- 



114 ELEMENTS OF DRAWING 

dimensions make up an " over all " (total dimension) no error has 
been made. 

3. See that related parts do not interfere; i.e., check each part 
with those parts to which it will he adjacent in the assembled 
machine, to see that corresponding dimensions agree, and that 
proper clearances have been allowed. 

4. See that dimensions are given correctly, so that no com- 
puting or scaling will he necessary when working with the draw- 
ing, and that notes and figures are plain and in the position in 
which the reader is most likely to look for them. 

5. See that no arrowheads are missing, and that all marks 
for feet and accents for inches are correct and none omitted. 

6. Lay out to scale and 07i a separate sheet the path of 
motion for moving parts, and see that the proper clearances are 
maintained in all positions. 

7. See that no center lines are missing, and that they are all 
correctly shown. 

8. See that finished surfaces are properly indicated. 

9. See that all stock material, such as screws, bolts, rivets, keys, 
etc., are as far as possible of standard size. 

10. Check supplementary notes and all instructions and every 
feature of the hill of material and title. 

In addition to the above see that alPthe instructions given 
in Appendix A, page 175, are carried out with reference to 
exercises in this course. 

77. Tracing. A tracing is an exact copy of a drawing, made 
by placing transparent cloth (see page 6, § 6) or paper (see 
page 6, § 5) over the drawing and tracing on this cloth or paper 
lines to correspond to those of the original drawing. 
B In commercial drafting rooms the tracing is the permanent 
record of the drawing and is used as a negative to produce addi- 
tional copies of the drawing, usually by the blueprint process.- 

To make a tracing, stretch the cloth over the drawing to be 
traced until it is fairly taut and perfectly smooth and even. 
Place a thumb tack in each corner, and a sufficient number around 
the edges to hold it flat and well stretched. Before beginning 
to ink, sprinkle the surface of the cloth with powdered chalk, 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE I15 

and rub lightly with a soft, clean rag to overcome the effects of 
any oil that may be present; then brush off the chalk with a clean 
rag so that it will not pile up in front of the pen when inking. 

Greater care is required to make a drawing on tracing cloth 
than on drawing paper, especially if the glazed side of the cloth 
is used. One very important precaution to be taken is 10 see 
that the pen is clean, sharp, and otherwise in good condition. 
The pen should carry less ink than when working on paper, 
as the ink has a greater tendency to spread. Take special 
care to draw the ink lines exactly over the pencil lines of 
the drawing being traced. Be very careful in inking lines 
that meet or intersect, since if the first line is not dry (ink 
dries slower on cloth than on paper) before the second is 
drawn, a blot will result at the point of meeting. Work only on 
one part of the tracing at a time, and whenever possible com- 
plete a view before leaving the drawing for any length of time, 
the reason for this being that moisture in the air affects the 
cloth, and may cause it to warp to such an extent that it 
will be difficult to complete the view later on. When the cloth 
warps, remove thumb tacks and readjust it to fit over the 
lines of the drawing as accurately as possible. Moisture will 
destroy the surface and transparency of tracing cloth, rendering 
it unfit for printing or drawing. For this reason avoid working 
on the cloth with damp hands. A tracing may be cleaned with 
a rag or sponge moistened with benzine or gasoKne. Never fold 
or crease tracing cloth. 

The same systematic order given for inking a drawing should 
be followed in tracing. See page no, § 75. 

Erasures on a tracing must be avoided as far as possible, but 
it is often necessary in practice to make complete changes of por- 
tions of a view, and for this reason the beginner must learn to 
make erasures without spoiling a tracing. After the erasure has 
been made, the smooth surface must be restored before again 
applying ink. To smooth the surface, rub the injured area with 
a soapstone pencil and polish with a cloth. See page 18, § 17. 

Never use a knife to scratch out lines on tracing cloth, as this 
may cause permanent injury to the surface of the cloth. In 
drawing over an erased area, set the pen for a finer line than is 



Il6 , ELEMENTS OF DRAWING 

required and build the line up to the required width by making 

several strokes. 

78. Blueprints. A tracing is used as a negative in reproduc- 
ing copies of a drawing by the blueprint process. Such prints 
are termed " blueprints " because the reproduced drawing is 
in white lines on a blue background. The prints are usually 
made in a printing frame, which is a device for holding the tracing 
and the prepared paper flat and smooth against a glass front. 
The right side of the tracing (i.e., the side on which the drawing 
has been made) is placed next to the glass; the chemically pre- 
pared side of the paper is placed next to the tracing and the 
back of the frame fastened down. The frame is then placed so 
that the glass front is exposed for a short time (the exact time 
depending on sensitiveness of the blueprint paper and the in- 
tensity of the sunlight) to the light and preferably to the direct 
rays of the sun, after which the exposed blueprint paper is 
taken out and washed in clean water. This method of printing 
depends more or less upon weather conditions, and to overcome 
all uncertainty and avoid delays, printing machines which print 
by electric light are used by many manufacturers. 

Changes and alterations on blue prints may be made by several 
methods. A solution of common soda and water, or quicklime 
and water, used as ink, will give a white line; but the best 
method is to use a white pencil for making new lines, and a blue 
pencil for striking out white lines. 

SET OF MECHANICAL DRAWING EXERCISES. 

'79. Drawing C-ioi. A mechanical detail drawing to full-size 
scale is to be made of the Lathe Spindle (see Fig. 77), the Key 




Fig. 77. — Perspective of Lathe Spindle. 



(see Fig. 78), the Fiber and Steel Washers (see Fig. 79), and the 
Special Nut (see Fig. 80). 

The purpose of the exercises on this drawing is to give practice 
in the use of the instruments required in making a simple me- 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE I17 

chanical drawing; to illustrate one method of arranging views, 
one method of dimensioning and lettering, the use of the title- 
form, the making up of a bill of material, and the use of the 
drawing-room system to be followed throughout this course. 





Fig. 78. — Perspective Fig. 79. — Perspective of Fiber 
of Key. or Steel Washer. 



Fig. 80. — Perspective 
of Special Nut. 



Study carefully the "Introductory," page 71, § 52, and "Detail 
Drawings," page 85, § 57, before attempting to draw. Also study 
the location and learn the purpose of each part on the assembled 
machine before drawing it. (See Frontispiece.) Fig. 82 shows 




Fig. 81. — Layout of Drawing C-ioi. 

the complete detail drawings of these parts, drawn to a reduced 
scale, and their location on the sheet is shown in Fig. 81. As 
it is essential to be able to arrange the views of a drawing 
symmetrically on the sheet, this is the only drawing in which 
the arrangement of views is given. It is also the only one for 



ii8 



ELEMENTS OF DRAWING 




MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 1 19 



which the bill of material and title has been made out. (See 
Fig. 83.) These features should therefore be noted carefully. 

Before starting on Drawing C-ioi read, and prepare for exam- 
ination, subjects taken up in paragraphs as follows: 

Introductory, page i, § i, — Drawing Paper, page 4, §3, 

— Drawing Boards, page 7, §8. — Thumb Tacks, page 8, §9, 

— T-squares, page 8, §10. — Triangles, page 10, §11.— Pen- 
cil Sharpener, page 14, §13. — Lead Pencils, page 14, §14. — 
Erasers and Erasures, page 16, §15. — Erasing Shield, page 17, 
§16. — Bow Pencils, page 27, §25. — Scales, page 29, §27. — 
Instrument Rag, page 33, § 30. — Introductory, page 34, §31. 



■f,^ 
i 





























/ 


rBR. 






S 


\/vashe:r 


/ 


M.S. 






^ 


WASHER 


£ 


MS. 






3 


SPECML NUr 


/ 


CR.S. 






a 


KEy 


/ 


•S. TUBE 






1 


SPINDLE 


SPEED LATHE DETAILS 


MACHINE DESIGN 

SIBLEY COLLEGE 

JTHACA. NEIA^ yORK 


DRA\A^N BV 


INSPECTED 

DATEAPR'i^D 


OR A WING- C 101 







Fig. 83. — Complete Title and Bill of Material for Drawing C-ioi. 



— Systematic Method in Lettering, page 44, §36. — Designing 
Headings and Titles, page 69, § 49. — Conventional Lines, page 
76, § 54. — Border Lines, page 106, § 72. — To Fasten the Paper 
or Tracing Cloth on the Drawing Board, page 107, § 73. — To 
Make a Pencil Drawing, page 108, § 74. — Checking Drawings, 
page 113, § 76. 

Before making this drawing also be prepared to answer ques- 
tions relating to mechanical construction as follows:^ For what 

^ Questions of this nature should be asked with reference to each draw- 
ing to be made in order that the beginner will realize from the start that 
there is a relation existing between drawing, machine design and shop work. 



I20 ELEMENTS OF DRAWING 

reason is the spindle finished to so many different diameters? 
What is the purpose of the hole through the spindle, also of the 
Morse taper at the end ? Why is the spindle made of steel ? 
Of what use is the Key, the Special Nut, and the Washers? 

Specific Instructions, {a) Tack down the sheet (see page 107, 
§ 73)- (^) Draw border line and title-form (see page 106, § 72, 
and page 100, § 66), and the bill of material form, shown in Fig. 
70, page loi. (c) With the rubber stamp print in the blank 
form shown on page 106, Fig. 72, just above the lower border line 
and to the left of the title-form, {d) Write in with ink your 
NAME (and initials), and fill in the DATE BEGUN, etc. 
(e) The center line of the spindle detail should then be drawn, 
not in its finished form and weight, but as a very light contin- 
uous line (see page 78, § 54). Study § 74, page 108, before actu- 
ally starting the drawing. After the outline of the view is 
completed, the center line can be made according to the conven- 
tional method, broken where necessary to allow for dimensions, 
and of the proper weight. Next, the outline of the spindle is 
drawn, in very light lines, after which the details of the view, also 
the section is drawn. The portion of any line extending beyond 
its proper limit must now be erased. When completed, all lines 
must be retraced and made the proper weight. (See page 76, 
§ 54.) Next draw in the reference lines, being careful to always 
leave a space next to the surface from which the line is extended. 
If this is not done, it appears that the lines have been drawn 
carelessly and that they extend beyond their proper limit. Put 
in all dimension lines and arrowheads and write in all dimen- 
sion figures and notes, always making them read from the bot- 
tom or right-hand side of the drawing. (/) The details of the 
key and the washer are to be next drawn. Since all details 
on this drawing are to be machine finished all over, the note 
" / " ALL OVER is printed near the part number of each de- 
tail, (g) Fill in the DATE FINISHED, TOTAL ACTUAL 
HOURS (required to complete the work), and the TITLE of 
the drawing. The Title of Drawing C-ioi is SPEED LATHE 
DETAILS, (h) Check the drawing (see page 113, § 76), to see 
that all lines, dimensions, and notes are correct, that the bill of 
material is correct, and that the part numbers (see page 104, § 69) 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 121 

have been put in. {i) Finally, have the drawing inspected, 
checked, and approved. (See page 175, Appendix A.) 

80. Tracing Drawing C-ioi. After the pencil drawing C-ioi 
has been approved it is to be traced. 

Before starting to trace this drawing read, and prepare for 
examination, the subjects taken up in paragraphs as follows : 

Tracing Cloth, page 6, §6. — Erasers and Erasures, page 
16, § 15. — Erasing Shield, page 17, § 16. — Soapstone, page 18, 
§ 17. — Drawing Ink, page 18, § 18. — Ordinary Pens, page 18, 
§19. — Penholders, page 20, §20. — Ruling Pens, page 20, 
§21. — Bow Pens, page 28, §26. — To Fasten the Paper or 
Tracing Cloth on the Drawing Board, page 107, §73. — Inking 
Drawings, page no, §75. — Tracing, page 114, §77. — Free- 
hand Inked Lines, page 136, § 96. 

Specific Instructions. Tack down the drawing "square" on 
the board and fasten the tracing cloth so that it lies smooth and 
close to the drawing with the glazed side up. (See page 114, § 77.) 

Chalk the tracing cloth and clean thoroughly with a soft rag. 

Ink the tracing according to the instruction given in § 75, 
page no. 

Remember that inked lines are of three weights: those repre- 
senting visible surfaces or outlines are drawn heavy; all construc- 
tion lines, reference lines, center Hnes, dimension lines, section 
lines, etc., are drawn light; and lines representing hidden sur- 
faces or parts are drawn medium, that is, one half the weight 
of visible lu-^es and twice the weight of center lines and dimen- 
sion lines. 

After the tracing is inked, thoroughly examine the work to see 
that nothing has been omitted, correct any errors, and when the 
tracing has been checked, submit it for approval, then follow 
instructions in § 81 this page. 

81. Blueprint of Tracing C-ioi. A blueprint is to be made 
of Tracing C-ioi before it is submitted for final approval. 
The purpose of making the blueprint at this time is to give 
the beginner the benefit of this experience before making a 
second tracing. Examine the print very carefully to see if all 



122 



ELEMENTS OF DRAWING 



lines are white and clear, and in case some are not, examine the 
tracing to find the reason, and profit by this knowledge in mak- 
ing succeeding tracings. All Blueprints must be trimmed and 
filed with the drawings and tracings. 

In connection with this exercise read, and prepare for exami- 
nation on, paragraphs, as follows: 

Tracing paper, page 6, § 5. — Blueprint Paper, page 6, 
§ 7. — Drawing Ink, page 18, § 18. — Blueprints, page 116, § 78. 

Having made a satisfactory blueprint, submit same for final 
approval. 

Any tracing spoiled by moisture in the process of blueprinting 
must be made over. 



82. Drawing C-102. A mechanical drawing 
of the Lathe Leg (see Fig. 84) is to be made 
one-quarter size. The purpose of this exer- 
cise is to introduce the problem of joining 
straight lines to curves, arranging views sym- 
metrically on the sheet, making a drawing to 
scale, listing patterns in the Bill of Material, 
and indicating finished surfaces ; to illustrate 
the use of cross sections and to provide 
practice in drawing, lettering, and dimen- 
sioning. Fig. 85 shows the views, etc. 

Before starting on Drawing C-102 read, 
and prepare for examination, the subjects 
taken up in paragraphs as follows : 

Soapstone, page 18, § 17. — Compasses, 
^g;^ page 23, §22. — Dividers, page 26, 
§ 23. — Bow Dividers, page 27, § 24. — 
The Study of Lettering, page 34, § 32. — Projection and Pro- 
jected Views, page 73, §53. — Choice of Scale in Drawing, 
page 93, § 61. — Title-form on a Drawing, page 100, § 66. — 
Bill of Material, page loi, § 67. — Numbering and Indicating 
the Size of Drawings, page 103, § 68. — Recording Patterns on a 
Drawing, page 104, § 70. 

Before making this drawing also be prepared to answer ques- 
tions as follows: 




Fig. 84. — Perspective of 
Lathe Leg. 



J." = I " 



-/ 



MECHANICAL DRAWING AND DRA52 
th -\ V . 



ROOM PRACTICE 1 23 




Fig. 8s. — Details for Drawing C-102. 



1 



I -> 



a- 



^y^ 



124 



ELEMENTS OF DRAWING 



State the reason for jGrnishing the surfaces as indicated. Ex- 
plain exactly how the legs and bed are held together. What 
is the purpose of the three ^f " drilled holes on the lathe bed? 
Explain the reason for selecting the cross section shown on the 
drawing. 

Specific Instructions, {a) Tack down sheet, {h) Draw bor- 
der line and title-form, (c) Stamp printed form jus*t above 
lower border ine and to left of title-form, {d) Write, with ink, 
NAME (and initials), fill in DATE BEGUN, etc. (e) Arrange 
views. See page 83, § 56, on Number and Arrangement of 
Views. (/) Proceed to make the drawing. See page 83, § 57, 
on Detail Drawing, (g) Fill in TITLE, BILL OF MATE- 
RIAL, DATE FINISHED, and TOTAL ACTUAL HOURS. 
The title of Drawing C-io2 is SPEED LATHE DETAILS. 
Qi) Check drawing, and submit for final approval. (See page 
175, Appendix A.) 




Fig. 86. — Perspective of Lathe Bed. 



83. Drawing C-103. A mechanical detail drawing (see 
Fig. 88) is to be made of the Lathe Bed (see Fig. 86) and the 
Bracket for the shelf (see Fig. 87), also the 
Standard Parts belonging to the above 
parts are to be listed in the Bill of Material. 
Following is a complete list of parts which 
are to be called for in the Bill of Material: 
Part #1 — Bed. 

Part tt2 — Y X ih" Square-head Cap 
Screw.* 
-|" X i" Square-head Cap Screw. 




Part tt3- 
Part tt4 



Bracket for shelf. 



Fig. 87. — Perspective of 
Shelf Bracket. 



Part if5— f " X lY Square-head Cap Screw. 
Before starting this exercise read and pre- 
pare for examination on paragraphs as follows: 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 125 




126 ELEMENTS OF DRAWING 

Introductory, page 71, § 52. — Conventional Lines, page 76, 
§ 54. — Sectioning and Sectional Views, page 79, § 55. — Num- 
ber and Arrangement of Views, page 83, § 56. — Detail Draw- 
ings, page 85, § 57. — Indicating the Finish of Surfaces, page 
98, § 64. — Part Numbers on a Drawing, page 104, § 69. 

Determine the number of each of these parts required, assign 
pattern numbers as necessary, etc. 

The drawing is to be made to a scale ofJ4'' = i ft., and the 
title of the drawing will be SPEED LATHE DETAILS. No 
drawing is made of the standard parts (see page 103, § 67), but 
their reference numbers must be properly shown on the drawing 
from which a " leader " must be run to the exact place that the 
standard part is used on the part detailed. 

Follow specific instructions given for preceding drawings^ in so 
far as they apply to this drawing. 

84. Drawing C-104. This drawing represents Bolts,, Nuts 
and Screws, and is intended to introduce the method of propor- 
tioning parts by empirical formulas, i.e., formulas which have not 
been "derived" by purely theoretical consideration; also it is 
intended to teach the relative proportions (or dimensions)' of 
U. S. (United States) Standard Bolts and Nuts. 

This drawing is further intended to teach the relative pro- 
portions of the ordinary forms of screw heads in common use, 
the conventional method of representing screw threads and the 
method of calling for all such parts in a Bill of Material. 

Before taking up this exercise read and be prepared for exam- 
ination on paragraphs as follows: 

Slope of Letters, page 36, §33. — Conventional Methods, 
page 87, § 59. 

It is coming to be more and more the common practice in the 
United States to use the U. S. form of thread, whether the piece 
threaded be a bolt, nut, screw or rod. 

In the case of screws the manufacturers of the United States 
are gradually adopting the A. S. M. E. (American Society of 
Mechanical Engineers) standard. 

Ordinarily none of these " standard " parts need be drawn 
out, but the exercises on this drawing will be very valuable to 



MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 127 



the beginner because they will associate in the mind the form and 
proportion, the number of threads per inch and the method of 
calling for such parts in the Bill of Material. 

Specific Instructions. Ideas as to this drawing can be gained 
by reference to Fig. 89, page 128. Having drawn the border line 
and the title-form, lay out and fill in the Bill of Material, the 
items being given below. The items in the Bill of Material 
can be abbreviated, but, owing to the limited space, it is even 
then necessary to compress the lettering which should be 
blocked out in very light Hues before being printed in final 
form. Care must be taken, however, to correctly space letters 
and words. 

The following items are to appear in the Bill of Material : 



Part tti 
Part ^2- 
Part #3 
Part tt4- 
Part tt5 - 
Part de- 
part #7- 
Part tt8- 



- i" X 6" Square-head Bolt, Nut, Check Nut. 
■^" X 6" Hexagon-head Bolt, Nut, Check Nut. 
■f" X 2^" Hexagon-head Cap Screw. 
I" X 2" Fillister-head Cap Screw, 
f" X 2" Round-head Cap Screw. 
I" X i|" Flat-head Cap Screw. 
I" X i|" Set Screw, 
•f" X i" Headless Set Screw. 



The following Table of Threads is to be placed exactly above, 
and f " from the Bill of Material. 



Diam. of Bolt. . 


1'/ 


A" 


3'/ 

8 


A" 


1" 

. 2 


A" 


5" 
8 


3 If 
4, 


111 
8 


i" 


i|" 


I2 


If" 


2" 


21" 


3" 


Threads per inch 


20 


18 


16 


14 


13 


12 


II 


10 


9 


8 


7 


6 


S 


4i 


4 


3l 



The title of this drawing is BOLTS, NUTS, AND SCREWS. 

The next step is to make substitutions in the formulas and 
work out the dimensions of the bolts, nuts, and screws. These 
computations must be neatly inked . on standard computation 
paper, and the sheets attached with paper fasteners to the 
drawing when it is handed in. 

As an illustration of how the computations are to be arranged. 
Item No. 7 is worked out as follows: 



128 



ELEMENTS OF DRAWING 




-i^--^ 



r«— r— =ri 



ft 


^'1 



CAP SCREW HEAD 



FILLISTER HEAD 





E=A: C=2A 

DISTANCE ACROSS FLAT=B 
iA + f^'wHEN A <^" 
M + x" WHEN A >-i" 



E= 
C= 



^^sl-^_ 



fA: B-iA 
^A; D=liA 

FLAT HEAD 



J7 






— -j^^ 



E-j%A; D=2A 



^, 




SET SCREW 






R=2D 



ROUND HEAD 




>_--^^ 



E=7A; B-zA 
C-kA; D-liA 



V — -^pCS 

FINISH FOR ENDS OF 

BOLTS. CAP SCREWS 

AND STLIDS 

4- 



FJNISH FOR ENDS OF 
MACHINE SCREWS 



Fig. 89. — " Standard " Proportions of Ordinary Nuts, Screw Heads, etc. 






MECHANICAL DRAWING AND DRAFTING ROOM PRACTICE 1 29 



/^em 


No. 


7- 








2 '^ 


I2 


Set Screw. 




£ = 


^ = 


. 1'/ 
• 2 • 








C = 


2 A 


= 2 


X 


111 

2 — 


l". 


5 = 


iA 


_ 7 

~ 8 


X 


1// 

2 — 


-h" 


D = 


lA 


_ 3 

~ 8 


X 


1'/ _ 

2 — 


tV. 



The computations for each item must be kept as shown, and 
as many items should be placed on a sheet as possible without 
crowding. 

Having computed the dimensions of all the parts to appear 
on Drawing C-104, block out the space to the best advantage, 
and complete the drawing, keeping in mind the following facts: 

Conventionally drawn threads begin and end with a short lint. 
(See page 72, Fig. 49.) 

Bolts are threaded any desired length, and the check nut is 
usually screwed on the bolt first, then the ordinary nut. 

Cap screws up to and including 1" diameter by 4" long are 
threaded for three-quarters of their length ar|,d those above 1" in 
diameter are threaded one-half their length. 

85. Tracing Drawing C-102. After submitting drawing C-104 
and making a blueprint of tracing C-ioi, trace the finally 
approved pencil drawing C-102. Follow specific instructions 
previously given in so far as they apply to this exercise. 

86. Tracing Drawing C-103. After submitting tracing C-102, 
trace the approved pencil drawing C- 1 03. Follow specific instruc- 
tions previously given in so far as they apply to this exercise. 

87. Drawing C-105. Make a mechanical drawing from 
sketches of the following parts: 

Tail Stock Center, see Fig. loi, page 144, also sketch #3, page 
r45. — Shell, see Fig. 104,, page 144, also sketch #4, page 146. 
— Tail Stock Spindle, see Fig. 103, page 144, also sketch #4, 
page 146. — Tail Stock Spindle Clamp, see Fig. 113, p. 150, 
the measurements of which are to be obtained directly from 
the part itself. 

Before starting this drawing read, and prepare for examina- 
tion on, paragraphs, as follows : 



130 ELEMENTS OF DRAWING 

Conventional Methods, page 87, §59. — Drawing to Scale, 
page 90, § 60. — Dimensioning Working Drawings, page 94, 
§62. — Notes on a Drawing, page 97, §63. — Indicating the 
Finish of Surfaces, page 98, §64. — Use of Record Forms and 
Titles, page 98, § 65. 

Follow specific instructions previously given in so far as they 
apply to this exercise. Give special attention to arranging the 
views and filling in the Bill of Material. 

88. Drawing C-106. Make a full-size longitudinal section of 
the Tail Stock with all its parts assembled. See Frontispiece. 

Before starting this drawing read, and prepare for examination 
on, paragraphs, as follows: 

Sectioning and Sectional Views, page 79, §55. — Assembly 
Drawings, page 86, §58. — Dimensioning Working Drawings, 
page 94, § 62. — Time Keeping in Drawing, page 105, § 71. 

Specific Instructions. To get all the necessary information 
for making this drawing refer to the approved Drawing C-105, 
also figures and sketches, as follows: 

Tail Stock Main Casting, Fig. 117, page 152, also sketch ^9, 
page 153. — Tail Stock Screw, Fig. 114, page 150, also sketch #8, 
page 151. — Tail Stock Hand Wheel, Fig. 107, page 147, also 
sketch ^5, page 148. — Tail Stock Special Nut, Fig. 115, page 
152, also sketch ^8, page 151. 

The title of this drawing is ASSEMBLED TAIL STOCK. 

Go over the drawing carefully before submitting same, to 
see that all lines, dimensions, etc., are up to the required 
standard. 

89. Tracing Drawing C-106. Follow specific instructions 
previously given in so far as they apply to this exercise. 

90. Examination on Chapter III. As a final examination any 
drawings assigned are to be made of Lathe Parts or of any other 
machine, and examination questions concerning previous work 
(including Drawing C-105) will be asked. As a general review, 
in preparation for examination, carefully read paragraphs on 
pages 71 to 79 inclusive; also § 12, page 13, and § 28, page 31. 



CHAPTER IV 

FREE-HAND WORKING SKETCHES 

91. Introductory. The ability to make a good free-hand work- 
ing sketch is an accomplishment of great value to the engineer. 
Much less time is required to make a free-hand sketch than a 
mechanical drawing, and in developing a design it frequently 
occurs that there are several solutions to the problem, and 
that the best may be as easily determined from a sketch as from 
a more elaborate mechanical drawing. If definite movements 
must be provided for, the vital positions of the related parts 
may be shown in skeleton outlines drawn to scale with instru- 
ments and each important element or part needed to be drawn 
can be sketched in free-hand. 

In commercial drafting rooms preliminary sketches of new 
ideas are often filed away to be worked up later into detail 
mechanical drawings. Such sketches serve as a visible record of 
the idea and may prove valuable in establishing a priority claim 
for a patent. 

Another common use of technical sketches is found in detail- 
ing parts that must be renewed and for which no drawings exist. 
Also in making additions or alterations, drawings of a machine 
may not be available and yet, in order that the new parts fit 
into position and act without interference, a drawing may be 
necessary. Whenever data must be obtained from machines in 
existence, a record of all measurements is usually made on a 
free-hand sketch, and the ability to make a clear sketch, accu- 
rately dimensioned, complete in all respects, and free from mis- 
takes and oversights so that additional trips to the machine for 
further information are not necessary, is of great value to the 
draftsman or engineer. 

92. Free-hand Copies of Working Drawings. To beginners 
the value of making free-hand sketches from mechanical draw- 
ings is to train the hand to make good free-hand lines, and the 

131 



132 ELEMENTS OF DRAWING 

eye to judge proportion^ so that the ability to scheme work and 
to plan details without using the drawing instruments will be 
acquired. 

93. Free-hand Sketches from Objects. It must be understood 
that working sketches as discussed here are not perspective 
representations of the object, but economical substitutes (both 
as to time and cost saved) for mechanical drawings. If the 
sketch is proportioned accurately (say on cross-section paper) 
in accordance with measurements of the object, it is in reality 
a working drawing, differing from a mechanical drawing only in 
that it is made free-hand. 

In making sketches from the object the beginner often con- 
siders the dimension figures the only important feature of the 
work, and makes the drawing so crude that other persons can- 
not work' from it. Such a sketch is of very little value. If a 
sketch is to be a permanent record it must be so clear and 
complete that any one will be able to work from it, and this can- 
not be done unless the actual drawing is well executed. On 
the other hand if the sketches accurately represent the object 
it may not be necessary to have all the dimensions recorded 
exactly as they measure on the object. For example, rough 
castings and forgings will vary in thickness, and a part in- 
tended to be symmetrical about a center line will often deviate 
without apparent reason. The beginner must learn to make a 
distinction between dimensions as some measurements must be 
recorded more exactly than others. For example, if a pipe 
flange measured 15J" in diameter, a 15" flange could be re- 
corded, but if the standard bolt circle of a pipe flange should 
be 13I," it must be so recorded, or the flange will not match 
others drilled according to the standard. The degree of refine- 
ment exercised in recording measurements between unfinished 
ends of a casting or between one finished and one rough end 
will depend on the size of the casting. In very small castings, 
such as the small parts of the lathe, dimensions can be fre- 
quently " rounded off " to, say, the nearest \", but measure- 
ments made between surfaces of parts which fit to other parts 
of a machine must be made with extreme accuracy. Center lines 



FREE-HAND WORKING SKETCHES 



133 



and lines of symmetry must also be carefully located, and 
wherever possible measurements should be made from such 
lines or from finished surfaces. 

A sketch made without direct measurements of the object 
has no definite scale but is proportioned hy the eye. In such 
cases the proper relation of distances, i.e., lengths of lines, is 
secured by making comparisons. The relative width of a part 
is compared to its length, and if a detail on the machine is one- 
fourth as long as the over-all dimension, it should be drawn one- 
fourth as long as the over-all on the drawing. To assist in 
making an eye estimate of a distance, hold the pencil between 
the eye and the object and so that the thumb nail can be moved 
along its length (see Fig. 90) ; sight along one end of the pencil 




Fig. 90. — Estimating Proportion by Means of the Eye and a Pencil. 

and bring it in line with the end of the part being measured; 
move the thumb along the pencil until it sights the opposite end. 
This length along the pencil is then compared with the length of 
the over-all dimension similarly measured. In the figure the 
two diverging lines represent the limits of the angle of sight. 
The left eye usually is closed when estimating. The special 
precautions necessary in this method are that the pencil shall 
always be held the same way and the same distance from the eye, 
and the lengths, being compared on the object, shall be approxi- 
mately the same distance from the eye. The pencil should be 
held at arm's length in making measurements, as this insures the 



134 ELEMENTS OF DRAWING 

distance being kept constant. In this method of estimating pro- 
portionate lengths no one estimated length should be greater than 
a convenient length on the pencil, but the distance from the eye 
to the object being sketched should be such that the estimating 
can be on the largest scale possible. The sketch can be made 
to any desired scale, provided the proportions of the sketch are kept 
the same as estimated with the pencil. This method of mak- 
ing a sketch of an object is equivalent to tracing each line of the 
object on a pane of glass which is held at arm's length and in 
a plane at right angles to an imaginary line drawn from the eye 
to the " center " of the object. 

94. Making Sketches from Memory. The beginner should 
occasionally make sketches from memory. For this purpose 
select some simple object, or mechanical drawing, and after 
making a careful study of the object or drawing, make free- 
hand sketches comprising all necessary views and accurately 
dimension them from memory. 

95. The Free-hand Pencil Line. The first essential in making 
free-hand sketches is to learn to draw a finished free-hand line. 
This requires, first, that the direction of the line and, second, that 
the quality of the line be correct. That is, the Hnes must 
have the proper direction and relation to one another to cor- 
rectly represent the outline of the object, and they must also 
be perfectly smooth and clear-cut, see page 78, § 54, so as to 
present a satisfactory appearance. 

A good method of drawing a free-hand straight line is as 
follows: 

(i) Sketch in very lightly a series of short dashes to follow as 
closely as possible the exact direction required of the line. See 
Fig. 91(a). 

(2) Correct the main portions which are out of true, locating these 
by sighting along the line and marking inaccuracies. See Fig. 91 (b) , 

(3) Retrace the line, which is now true in direction but "sketchy^' 
in quality, making it uniform and of medium weight. See 
Fig, 91(c). 

(4) Erase all preliminary work, and, as the true line is made 



FREE-HAND WORKING SKETCHES 



135 



dim in the process, retrace it with the longest strokes possible, leav- 
ing it true in direction and finished in quality. See Fig. 91(d). 



A- 



B 



Use a HHHH pencil 

with conical point (see (a) First Attempt to Get Correct Direction. 

page 15, § 14), and as the /\ — =*= — ^ q- ■; b 

first attempt will seldom C'') corrections Made at Points of inaccurate Direction. 



result in a line true in 
either direction or qual- 
ity, all preliminary work 
must be done with very- 
light lines. The pencil 
should be moved toward the right [see Fig. 92(a)] when drawing 
lines which are horizontal or nearly so, and toward the body or 



A—^-^ -^— - — "^^ -B 

(c) Line Perfected in Direction but not Quality. 

A— ■ • a 

(d) Line Perfected in Both Direction and Quality. 
Fig. 91. — Drawing a Free-hand Line. 




(a) Drawing a Horizontal Free-hand Line. 




(b) Drawing a Vertical Free-hand Line. 
Fig. 92. — Method of Holding the Pencil to Draw a Free-hand Line. 

downward [see Fig. 92(b)] when drawing lines which are vertical 
or nearly so. In drawing free-hand lines it is very important 



136 ELEMENTS OF DRAWING 

that the pencil be held " freely " and not with a strained grip 
and the relation of the pencil, the fingers and the paper is 
shown in Fig. 92. Motion to the pencil or pen should not be 
given by movement of the fingers but by an easy movement of 
the hand and forearm. When a finished line, straight or curved, 
is drawn with more than one stroke of the pencil, considerable 
care must be exercised in joining the segments, so that the line 
will be continuous and appear to have been drawn at a single 
stroke. A curved line is drawn by locating a series of points to 
mark its direction, and then proceeding as with the straight line. 
Do not erase the first lines drawn but only that portion which does 
not follow the direction desired. This leaves portions of the fine 
to act as a guide and the final line is brought to its proper direc- 
tion and traced in somewhat heavier than the preliminary lines. 
When a line has been drawn exact in direction, all preliminary 
work, and as much of the true line as is necessary to destroy the 
appearance of the short sketchy strokes, is erased (using a clean 
eraser and when necessary an eraser shield), and the line is finally 
retraced and made of satisfactory quality. 

96. Free-hand Inked Lines. The beginner should not ink 
any work unless the original pencil work has been checked and 
approved. 

To draw an inked free-hand line, fill the pen with an average 
amount of ink, and, holding the point at the beginning of the line, 
slightly press the pen until the ink begins to flow (which is indi- 
cated by a dot of ink on the drawing), then with an even pressure 
continue from that point, making the line uniform in width from 
start to finish. 

The width of the free-hand inked line will depend on the 
following conditions: 

(i) Fineness of the pen point. 

(2) Pressure exerted on the pen. 

(3) Condition of the pen point as regards cleaniness, i. e., 
whether there is dried or partially dried ink on the point. 

(4) Amount of ink carried on the pen. 

(5) Speed at which the pen is moved when drawing the line. 



FREE-HAND WORKING SKETCHES 137 

In general, free-hand inked lines should be formed with strokes 
toward the draftsman, Or in a right-hand direction. (See Fig. 92, 
page 135.) Upward strokes of the pen should be avoided as much 
as possible, as the pen point is liable to catch in the drawing 
and splash the ink; also this is not the most natural way to 
make free-hand lines. 

Care must be exercised in joining two segments of a line when 
inking, otherwise the point at which they are joined is easily 
detected and the completed line will not present a finished 
appearance. 

To get the best results there should be a steady and uniform 
flow of ink from the pen, and this is best secured by frequently 
cleaning and refilling the pen. 

Too much ink on the pen will make a blot or a line of greater 
width than desired, while too little ink dries upon the points 
and obstructs the free flow of the ink from above. Frequent 
filling of the pen tends to maintain an average quantity of ink 
and overcomes both of these difficulties. If too much ink has 
been gathered on the pen point touch the pen to the neck of 
the bottle to permit the surplus ink to flow back into the bottle. 

Always clean the pen point thoroughly before putting it away. 

97. Building up a Sketch. To start a sketch, study the 
part to be represented and determine the view which shows the 
most essential features and from which related views can be best 
obtained. The relation of views and the principles underlying 
machine sketching are exactly the same as for mechanical drawings. 
(See page 73, § 53.) 

Having determined the views (and sections, if any are neces- 
sary) and the size of the views, draw in the main center lines in 
such a position that when the views are completed they will 
be arranged symmetrically on the sheet and present a neat 
appearance. 

In beginning each view, draw several of the most important 
limiting lines first, and then fill in the detail parts. 

In general it is best to work from the center of a view, i.e., 
from the center lines, or from the central parts outward. 

Always complete the views satisfactorily before putting in 
reference lines, dimension lines, and arrowheads. 



138 ELEMENTS OF DRAWING 

The outline of one view should be completed as far as possible 
before starting another. In working up views it is often con- 
venient to use a strip of paper to transfer the principal dimen- 
sions from one view to another. When a circle or circular arc 
is to be drawn, several points should be marked off equally distant 
from the center and the curve drawn through them. 

In some cases it may be found best to draw in the principal 
dimensions of the object to scale and finish up the detail parts 
of a view free-hand; but sketching as a rule is not done to scale, 
although the proportions are made approximately correct. 

Draw in all the dimension lines and arrowheads, but do not 
put in dimension figures until the last. 

Draw all lines very lightly at first, and, after inaccuracies have 
been corrected, retrace the sketch and make the lines of medium 
weight. 

When the correct outlines of all views have been drawn of 
medium weight, the entire sheet is to be cleaned with the sponge 
rubber or art gum (see page 16, § 15), and such other erasing done 
with the pencil eraser as is necessary. Then all the dimmed lines 
of the views should be retraced and made of the desired weight. 

98. Title-form on Small Sheets. Where the drawing sheet is 
small a small title-form is preferable, and this title-form is usu- 
ally located in the lower right-hand corner. 

1^ ^'- — *4 

1 I 



TITLE. 



MACHINE DESIGN-SIBLEY COLLEGE- IT H/\C A, NY 



NAME SECTION^ DESK A/^ 



BEGUN FINISHED TOTAL HRS. 



INSPECTED ARR VD.. 



SHEET..., 



Fig. 93. — Title-form to be used in this work on small sheets. 

There is no accepted standard title-form, but the one shown 
in Fig. 93 represents a general average and will be used in this 
work on all drawing sheets of the 8" X io|" size. 



FREE-HAND WORKING SKETCHES 139 

All lettering in title-form, unless otherwise speciiied, is to be 
of the slant Gothic style and is to be carefully arranged and 
properly proportioned. 

99. Size and Numbering of Sketch Sheets. Exercises in 
sketching will be. done on small sheets of standard letter size 
(8" X 1O2"); heavy weight, cross-section paper ruled on one side 
(see page 5, § 4) and punched for standard ft 10 Manila cover. 

The order in which free-hand sketch sheets are executed will 
be indicated by Arabic numbers beginning with No. i and con- 
tinuing as far as necessary, and the title-form is to be as shown 
in Fig. 93, page 138. 

SET OF FREE-HAND DRAWING EXERCISES 

100. Sheet Si. The sketches on this sheet consist of 
a Shim (see Fig. 94) for the bearings, a Small Stud (see 
Fig. 95) and a Clamp, Stud (see 
Fig. 96) for the tail stock of the 
Lathe. Fig. 97, page 140, shows 
the general layout of this sheet. 

The exercises on this sheet give ^'^- 94. -Perspective of Shim. 

practice in making sketches of objects requiring only 
one view, and in drawing free-hand lines and arrow- 
heads. Note especially how the diameters of 
bolts are shown. This method applies to such 
parts as bolts, screws, etc., but the diameters of 
circular parts in general should be given on the 
view showing the circle. 

Before beginning this sheet determine, either 

Fig. 95. — 

from referring to the actual machine or else to Perspec- 
the frontispiece, exactly where each piece is *g^®^°* 
H located, and its purpose on the finished ma- 
Fig. 96.— chine, also what other parts it must fit into or against. 
Perspec- YoT fuU information as to the general system to be 

tive of ATA 

Clamp followed scc page 175, Appendix A. 
^'"*^' Study, and prepare for examination on, paragraphs, as 
follows : 

Thumb Tacks, page 8, §9. — Pencil Pointer, page 14, § 13. 




ELEMENTS OF DRAWING 





1 r 



-^ k 



FREE-HAND WORKING SKETCHES 141 

— Lead Pencils, page 14, § 14. — Erasers and Erasures, page 16, 
§ 15. — Conventional Lines, page 76, § 54. — Checking Drawings, 
page 113, § 76. — Litroductory, page 131, § 91. — The Free-hand 
Pencil Line, page 134, § 95. — Title-form for Sheets, page 138, 
§ 98. — Size and Numbering of Sketch Sheet, page 139, § 99. 

Specific Instructions, (a) Fasten the sheet on the small draw- 
ing board. (See page 2, § 2.) (b) Stamp in and fill out Title- 
form. (See page 138, § 98.) The title of this sketch is LATHE 
DETAILS, (c) Copy the sketches, being careful to see that 
the work is correct in every particular. 

Use a HHHH pencil and draw the sketches free-hand on cross- 
section paper. Group the figures centrally on the sheet in about 
the relative position and proportion shown in Fig. 97, page 140. 

In making the sketch of the Stud, the center line is drawn first 
and the sketch built symmetrically about it. All center lines, ref- 
erence hues, dimension fines, and arrowheads are to be drawn in. 

Do not make any measurements with scale or dividers, but 
proportion the sketches'by eye. (Seepage 133, §93.) {d) Thor- 
oughly examine the work to see that nothing has been omitted; 
correct any errors, and after inspection write, with ink, the Date 
Finished and Total Actual Hours, and submit the sheet for 
checking and approval. 

. loi. Sheet S2. The sketch on this sheet (see Fig. 99, page 143) 
consists of three views of the main casting of the Headstock (see 
Fig. 98, page 142) of the Lathe. All dimension figures on Fig. 99 
represent the number of spaces between arrowheads and not the 
number of inches. 

The purpose of this exercise is to illustrate the use of cross- 
section paper; to provide practice in making free-hand curved 
fines, and in making a sketch of an object which requires several 
views. 

The relation of the different views of this sketch to one another 
must be carefully studied, and the sketch not merely copied. . 

Before starting this work read, and be prepared for examina- 
tion on, paragraphs, as follows: 

Cross-section Paper, page 5, §4. — Erasing Shield, page 17, 
§ 16. — Projection and Projected Views, page 73, § 53. — Num- 



142 



ELEMENTS OF DRAWING 



ber and Arrangement of Views, page 83, §56. — Dimension- 
ing Working Drawings, page 94, §62. — Indicating the Finish 
of Surfaces, page 98, § 64. — Free-hand Copies of Working 
Drawings, page 131, § 92. 




Fig. 98. — Perspective of Main Casting of Headstock. 

Determine the location and purpose of the Headstock. See 
Frontispiece. 

Specific Instructions, (a) Fasten the sheet On the small draw- 
ing board. (See page 2, § 2.) (b) Stamp in and fill out title- 
form. (Seepage 138, § 98.) The title of this sketch is LATHE 
DETAILS, (c) Having located main center lines, refer to the 
" space dimensions " given in Fig. 99 and accurately locate a 
sufficient number of points to determine, the outline of the side 
view (a), which is then sketched in very lightly. The end views 
are next drawn. 

After all views have been completed in a satisfactory manner, 
clean the sheet and retrace all lines, making them clear-cut and 
of the desired weight. 

Having gone over the work and brought it to the highest 
standard possible, submit the sheet for approval. 



102. Sheet #3- The sketches on this sheet represent a Face 
Plate (see Fig. 100, page 144), a Tail Stock Center (see Fig. loi, 



144 



ELEMENTS OF DRAWING 




page 144), and a Special Nut (see Fig. 80, page 117) for head- 
stock spindle. Fig. 104 shows the general layout of this sheet. 
The purpose of the exercises on this 
sheet is to provide practice in free-hand 
sketching and in making a working draw- 
ing which will have all dimensions, notes, 
and other data necessary for the construc- 
tion of the parts in the shop. Before 
starting this sheet study the system of 
dimensioning, noting especially how circles, 
arcs, angles, and tap'ers are dimensioned, 
and how related dimen- 
Fig. 100. — Perspective of g^Qng ^re kept together. 

Study and prepare Fig. loi. — Perspective of 

for examination on paragraphs as follows : 

Detail Drawings, page 85, §57. — Conventional Methods, 
page 87, § 59. — Indicating the Finish of Surfaces, page 98, 
§ 64. — Use of Record Forms and Titles, page 98, 1 65. — Making 
Sketches from Memory, page 134, § 94. 

What is meant by " counterbore " and " countersink." How 
do you determine the number of threads per inch on a given 
diameter ? 

Follow the specific instructions previously given in so far as they 

apply to this sheet. 




103. Sheet fi4. 

Fig. io..-Perspective of TaUstock Spindle. r^^^ exercisCS ' OU this 

sheet are sketches of the Tail Stock Spindle (see Fig. 102) and 
Shell (see Fig, 103). 

These exercises illustrate the method 
of representing simple symmetrical parts 
in the clearest way possible with the 
minimum amount of drawing. Fig. 
105 gives the general layout of this 
sheet. 

Before starting this work read, and be prepared for examina- 
tion on, paragraphs, as follows: 




Fig. 103.— Perspective of Shell. 



FREE-HAND WORKING SKETCHES 



145 





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FREE-HAND WORKING SKETCHES 



147 




Sectioning and Sectional Views, page 79, § 55. — Notes 
on a Drawing, page 97, § 63. — The Title form on a 
Drawing, page 100, § 66. 

104. Sheet #5. The exercises on this sheet consist of 

sketches of the Clamp Bolt (see Fig. 106) the Hand 

Wheel (see Fig. 107) and the End Cap (see Fig. 108). 

Fig. 109, page 148, gives the general layout of sheet. 

The system of dimensioning is the main point to be 

noted in sketching these 
parts. Dimensions which 
are related are kept to- 
gether, as, for example, the 
partial .dimensions making 
up the length of the Clamp 
Bolt. These are given on 

° _ Fig. 106.— 

the same side of the view Perspective 

and not scattered. With °^ '^^^^ 
partial dimensions, an over- 
all dimension is given, which of 
course must be the sum of the 
partial dimensions. 
Note also the method of dimensioning curves; the different 
views in which the different diameters are shown on the draw- 
ing; the method of " turning up " the section 
in the arm of the hand wheel, and that in the 
section of the hand wheel the arms are not 
sectioned, although the cutting plane passes 
through them. 



Fig. 107. — Perspective of Hand Wheel. 



105. Sheet #6. The exercises on this sheet 
consist of three undimensioned views of the 
Clamp (see Fig. in, page 150). Fig. 




Fig. 108. — Perspective 
of End Cap. 



no. 



page 149, gives the general layout of this sheet which is to be 
copied and then the dimensions filled in from measurements 
taken on the Clamp that the drawing illustrates. 

Before drawing this sheet read, and be prepared for examina- 
tion on, paragraphs, as follows: 



148 



ELEMENTS OF DRAWING 




FREE-HAND WORKING SKETCHES 



149 













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I50 



ELEMENTS OF DRAWING 



Machinist's Calipers, Dividers and Steel Rule, page 32, § 29. 

-Choice of Scale in Drawing, page 93, §61. — Dimensioning 

Working Drawings, page 94, § 62. 
— Notes on a Drawing, page 97, 
§ 63. — To make a Pencil Draw- 
ing, page 108, § 74. — Free-hand 
Sketches from Objects, page 132, 

§93- 




Fig. III. 



-Perspective of Tails tock 
Clamp Strip. 



106. Sheet 1^7. Make sketches 
of the Tool Rest Support Slide, 
(see Fig. 112) and of Clamp for 
113). This sheet is to be made 




Fig. 112. — Perspective of Tool Rest Support Slide. 



Tailstock Spindle (see Fig. 
directly from these parts:'" 

Before starting the " 
work read, and be 
prepared for exam- 
ination on, para- 
graphs, as follows: 

Projection and 
Projected Views, 

page 73, § 53. — Drawing to Scale, page 90, § 60. — Notes on a 
Drawing, page 97, § 63. — Building up a Sketch, page 137, § 97. 

Determine the pur- 
pose and location of the 
W above parts on the lathe. 

107. Sheet S8. Make 
sketches of the Tailstock 
Screw (see Fig. 114) 
and the Nut (see Fig. 

Fig. 113. — Perspective of Tailstock Spindle Clamp. \ r n 

115) lollowmg the gen- 
eral layout shown in Fig. 116, page 151. Determine the location 
and purpose of each of these parts on the lathe and be prepared for 





Fig. 114. — Perspective of Tailstock Screw. 



Fig. 115. — Perspective 
of Tailstock Nut 



FREE-HAND WORKING SKETCHES 



151 



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152 



ELEMENTS OF DRAWING 



examination on paragraph 59, page 87, with reference to 
Conventional Methods. 

Copy sketch and fill in dimension figures from measurements 
made on the objects which are illustrated. 

This sheet illustrates the method of showing and dimensioning 
key ways and the Acme National Thread (see page 88, section D, 
drawing C). Notice that the direction of the thread shown on 
the section of the nut is reversed from that on the screw and 
be able to explain the 
reason for this. 



108. Sheet #9- Make a 
working sketch, showing 
three views of the main 
casting of the Tailstock 
(see Fig. 117). 

Keep that portion of 
the surface of the draw- 
ing not in use covered 
with a clean piece of paper 
and avoid smearing the 
drawing. Fig. 119, page 
153, shows the general lay- 
out for this sheet. 




Fig. 117. — Perspective of Main Casting of Tailstock. 



109, Sheet ftio. Make working sketches 
directly from the Bearing Cap (see Fig. 118) and 
The Stationary Flange (see Fig. 120, page 154). 

no. Sheet #11. Make working sketches of 
the Cone Pulley (see Fig. 121, page 154), on 
Fig. 118.— Perspective ordinary standard size paper {not cross-section 

of Bearing Cap. ^ , , i , , i • n 

paper) and see that the views are well pro- 




portioned, 
paper. 



In practice sketches are frequently made on unruled 



III. Sheet #12. Make a copy of the sketch of the pattern 
and core box for the Cone Pulley (see Fig. 122, page 155). 



FREE-HAND WORKING SKETCHES. 



153 





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154 



ELEMENTS OF DRAWING 



112. Inking Sheet fti. The purpose of inking this sheet is to 
give practice in making straight free-hand inked lines. 

Where only a Hmited number of pieces are to be made from a 
drawing, it frequently happens that the work does not warrant 
the expense of making a tracing and a penciled sketch is not 
sufficiently permanent, therefore an inked sketch is made. 

Before starting this exercise study, and be 
prepared for examination on, paragraphs, as 
follows : 

Drawing Ink, page i8, § i8. — Ordinary Pens, 
page i8, § 19. — Penholders, page 20, §20. — 
Conventional Lines, page 76, § 54. — The Free- 
hand Inked Line, page 136, § 96. 

To avoid spoiling a pencil drawing practice 
making an inked line on a piece of scrap paper 
before starting to ink the penciled work. Do not 
start inking until the penciled sketch has been 
tiveoTsmau Flange, chcckcd and approved. 




113. Inking Sheet tf3- The purpose of inking this sheet is 
to give practice in making inked curved lines free-hand. 



114. Inking Sheet 

ftii. This exercise gives 
practice in inking on 
ordinary paper. 

115. Examination on 
Chapter IV. As a final ex- 
amination, any sketches 
assigned are to be made 
in pencil or in ink of 
Lathe Parts or parts of 
any other machine, this 

work to be done on Fig. x^x. -Perspective of ConePuUey. 

plotting or on plain paper as directed. Also examination ques- 
tions concerning the main subject matter of this chapter will 
be asked. 




FREE-HAND WORKING SKETCHES 



155 




CHAPTER V 

ISOMETRIC DRAWING AND SKETCHING 

ii6. Introductory. Isometric drawings are often preferable 
to mechanical drawings because they are very easily understood, 
even by those who have little or no knowledge of technical 
drawing. 

While mechanical drawings can be made so that they com- 
pletely represent an object both as to its form and dimensions, 
several views are usually required to represent the object fully; 
and in order to read and understand such drawings it is necessary 
to visualize the object Jrom these views. This usually requires 
considerable study on the part of the reader, and the disadvan- 
tages of mechanical drawings can be largely overcome by the 
use of isometric drawings to represent the object. Isometrics 
are coming to be used much more frequently in illustrating pip- 
ing plans and layouts, structural details, " bird's eye " views of 
buildings, "etc., although they have already been extensively 
used in making patent office drawings and in illustrating tech- 
nical books and catalogues. Isometrics are also especially useful 
in illustrating shop processes and methods, and certain manu- 
facturing firms operating under the so-called ''scientific manage- 
ment " use this method of giving very definite and minute 
instructions to the workmen, as, for examples, the best method 
of fastening a certain piece of work in a machine, the proper way 
to take cuts from the piece, etc. Some of the large steel manu- 
facturers are using isometric drawings practically to the exclusion 
of mechanical drawings. 

Some of the advantages of isometric drawings are: {a) they 
can be easily made and understood; (&) they give, in a single 
view, the information that requires two or more views if a me- 
chanical drawing is made use of; (c) practically no ability to 
" visualize " is necessary in reading isometric drawings, and in 
this respect they resemble perspective drawings but possess an 

is6 



ISOMETRIC DRAWING AND SKETCHING 157 

advantage over perspective drawings in that they can, in a 
limited way, be measured and dimensioned similarly to 
mechanical drawings. 

Some of the disadvantages of isometric drawings are : {a) they 
show an object " distorted " and often make it appear unreal; 
(b) they can be measured (i.e., " scaled ") only in certain direc- 
tions; (c) angles shown in isometric cannot be measured in 
degrees; {d) all circles show in isometric as ellipses, and an ellipse 
is more difficult to draw with instruments than a circle, but this 
is rather an advantage in free-hand isometric drawing. 

117. Principles. Isometric drawing is based on the principles 
of isometric projection, but it is beyond the scope of this text to 
take up the discussion of the principles underlying this art. For 
the purpose of this work it will be necessary to state only two new 
principles not included in orthographic projection, viz: 

(i) The object to be represented is so placed with reference 
to the projection plane that instead of presenting a single face for 
projection, three faces at right angles to each other and repre- 
senting the length, width, and thickness of the object will be 
equally inclined to this projection plane and thus all three faces 
are presented in a single view. 

(2) With an object placed as stated in principle (i) above, all 
vertical lines of the object will be drawn vertical, and all hori- 
zontal lines of the object will be drawn at 60 degrees to the 
vertical or at 30 degrees to a true horizontal line. 

These principles can be best illustrated by making an isometric 
drawing of a cube. See § 118, this page. 

118. Isometric Drawing of a Cube. A mechanical drawing 
of a cube is shown in Fig. 123 (a) and an isometric drawing of the 
same size cube is shown in Fig. 123 (b), see page 158. 

To construct the isometric drawing, draw the vertical line 0-Y 
and lay off B-F equal in length to the edge B-F of the cube; 
that is, equal to h'-f. 

From O draw 0-X to the left and 0-Z to the right, each line 
making 120 degrees with 0-Y; that is, each of these lines will 
make 30 degrees with a horizontal line. 



iS8 



ELEMENTS OF DRAWING 



On 0-X lay off a distance equal to the length of the edge 
B-A of the cube; that is, equal to b'-a'. 

On 0-Z lay off a distance equal to the edge B-C of the cube; 
that is, equal to b'-c'. 

. From A draw A-D equal and parallel to B-C. From C draw 
C-D equal and parallel to B~A. The rhombus* A-B-C-D is 
the isometric drawing of the square top a-b-c-d of the cube. 




(a) Mechanical. 



Fig. 123. — Drawing of Cube. 



(b) Isometric. 



From C draw C-G equal and parallel to B-F and from F draw 
F-G equal and parallel to B-C. The rhombus F-B-C-G is the 
isometric drawing of the square ia,cej'-b'-c'-g' of the cube. 

The face A-B-F-E is similarly determined. 

119. Definitions. The following definitions will be more easily 
remembered by referring to Fig. 123 (b), this page. 

(a) The isometric axes are three intersecting lines drawn at 
120 degrees to one another, one of which lines is vertical, and the 
other two will be 30 degrees to the true horizontal and in opposite 
directions. The isometric axes are sometimes referred to as the 
X, Y, and Z axes. 

{b) The isometric origin is the intersection of the isometric 
axes and it is usually marked O. 

(c) An isometric line is one which is parallel to any one of the 
three isometric axes. 

{d) A non-isometric line is one which is not parallel to any one 
of the three isometric axes. 

* The rhombus (or rhomb) is an oblique parallelogram whose sides are ail equal. 



ISOMETRIC DRAWING AND SKETCHING 



159 



{e) Measurements can only be made on isometric lines and 

can never be made on non-isometric lines. That is, an isometric 
drawing of a solid can be measured or scaled in only three direc- 
tions and of a plane figure in only two directions, these directions 
always being parallel to the isometric axes. This principle is 
illustrated in Fig. 123 (b), page 158. Lines which lie in the face 
B-C-G-F can be scaled, or measured, if parallel to 0-Z or 0-Y 
but not if parallel to 0-X. This will be understood if diagonals 
are drawn from BtoG and from F to C, for though these diagonals 
are actually equal in length they do not project equally. 











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120. Isometric Drawing of a Circle. The isometric drawing 
of a circle is always an ellipse. To determine points on the ellipse 
enclose the circle within a square as shown in Fig. 124 (a) and 
next draw the construction lines 1-2, j-4, 5-6, etc., so as to in- 
tersect on the circle at points i, j, k, I. Let it be assumed that 
the circle lies in a 
vertical plane. Then 
the isometric drawing d e f 
of the circumscribed 
square a-b-c-d can be 
drawn exactly as if it 
were the face F-G-C-B 
shown in Fig. 123 (b), 
page 158. The sides 
of the square a-d and 
d-c are made to coin- 
cide with the isometric 
axes 0-Y and 0-Z, respectively, in Fig. 124 (b), hence D-6 
of Fig. 124 (b) can be measured off equal to d-6 of Fig. 124 (a) 
and D-i of Fig. 124 (b) can be made equal to d-i of Fig. 124 (a). 
The points j and 8 of Fig. 124 (b) are found in a similar manner, 
and through the points 7, (5, etc., the construction lines are drawn 
parallel to D-C and D-A ; these lines, such as 7-2, and 6-5, are 
isometric lines and their intersection / is the isometric position 
of J, a point on the circle. All other points on the circle, such as 
E, I, H, etc., are similarly located and the ellipse which is drawn 
through these points is the isometric drawing of the circle. The 



(a) Mechanical. 




A 

y 

(b) Isometric. 
Fig. 124. — Drawing of Circle. 



i6o 



.EMENTS OF DRAWING 



ellipse through Ii-Ji-Ki-Li represents the isometric drawing of 
the same circle when it lies in a vertical plane parallel to the 
plane of the isometric axes 0-Y and 0-X. The ellipse through 
I2-J2-K2-L2 represents the isometric drawing of the circle when 
it lies in a horizontal plane. The points on these ellipses are found 
exactly as the points /-/- K-L of the first ellipse were found. 

121. Approximate Method of Making an Isometric Drawing 
of a Circle. The ellipse when constructed as described in § 120, 
page 159, represents the true isometric drawing of the circle, but 
an approximate method which is much 
simpler and at the same time sufficiently 
accurate for most purposes is shown in 
Fig. 125. The sides C-D and D-A are 
bisected respectively by the lines B-A 
and E-C, which are drawn directly from 
A and C with the 30-60 degree triangle. 
With C as a center and C-E as a radius 
describe the arc E-F. With J. as a 
center and with C~E as a radius describe 
the arc G-B. With the intersection 
point P of the lines A-B and C-E as a center and with P-E as 
a radius describe the arc E-B. Similarly describe the arc F-G. 
If this work has been accurately done the resulting figure will 
appear as a " smooth " ellipse. The ellipses in the vertical 
planes can be similarly constructed. 




Fig. 125. — Approximate Method 
of Drawing an Isometric of a 
Circle. 



122. Isometric Drawing of a Plane Figure Composed of 
Straight and Curved 
Lines. Assume that any 
plane outline as shown"' 
in Fig. 126 (a) is to be 




represented in isometric. 

Circumscribe a square or 

rectangle about the figure-4!'2 3 45 e ? bd 

to be drawn in isometric ^^^ Mechanical. 

as shown in Fig. 126 ^'' 

, , . (b) Isometric, 

(a). Through important pig. 126. — Drawing of Any Plane Figure. 



ISOMETRIC DRAWING AND SKETCHING 



l6i 



points on the figure draw lines parallel to the sides of the circum- 
scribed square. These lines will be isometric lines of the isometric 
drawing, hence I-K, K-6, K-F, F-j, etc., of Fig. 126(b) are 
drawn respectively equal to I-K, K-6, K-F, F-j, etc., of Fig. 
126 (a); the isometric position of the points such as E, F, K 
being found by laying off A-i, 1-2, 2-j, j-4, etc., D-I, I-II, 
II-JII, etc., of Fig. 126 (b), equal to the corresponding distances 
of Fig. 126 (a). Through these points, lines are drawn parallel 
to the proper sides of the rhombus and the intersections of these 
lines determine the isometric position of the required points. 

Fig. 126 (b) shows the figure in the horizontal and in the two 
different vertical isometric planes. 

123. Isometric Drawing of a Cube Cut by a Plane. Assume 
the cube cut by a plane through its edge and at any angle. First 
draw one face of the 
cube in orthographic 
projection, and draw 
the lines O-15, 0-jo, 
O-45, etc., from the 
corner and making 
15 degrees, 30 degrees, 
etc. , respectively, with 
the line 0-0, see Fig. ^, ^ 

' o (b) Isometnc. 




(a) Mechanical 




Cube cut by Planes. 



127 (a). In Fig. 127 (b) is shown the isometric drawing of 
this face of the cube with the lines O-15, 0-jo, etc., represented 
as making 15 degrees, 30 degrees, etc., with 0-0. In this figure 
the included corresponding angles are not equal to those of 



l62 



ELEMENTS OF DRAWING 






(a) Mechanical 



Fig. 127 (a), but the distances O-75, 0-jo, etc., measured on 
the bottom line of Fig. 127 (b) are equal to the corresponding 
distances of Fig. 127 (a). 

In Fig. 127 (c) a cube is shown in isometric as it would appear if 
cut by a plane through the edge 0-^ , and at 60 degrees to 0-0. 

In Fig. 127 (d) a cube is shown in isometric as if cut by two 
planes, one at 15°, the other at 60° with the back top edge 0-D. 

In Fig. 127 (e) a cube is shown in isometric as it would appear 
if cut, first, as in Fig. 127 (c), and then as in 127 (d). 

124. Isometric Drawing of Wall. Fig. 1 28 (a) shows a mechan- 
ical (or orthographic) drawing of a rectangular 
object, and Fig. 128 (b) shows isometric draw- 
ings of the block in three different positions. 
Fig. 128 (c) shows an 
ordinary isometric draw- 
ing which represents a 
wall built of blocks as 
shown in Fig. 128 (b). 
Fig. 128 (d) shows a 
different view of a wall 
similar to that of Fig. 
128 (c) but having the 
horizontal lines in a 
downward direction 
instead of upward as 
in previous work. 
Drawing the horizon- 
tal downward is called 
reversing the axes, and 
this method can be 
used to show the lower 
face of an object, rep- 
resenting it as if tilted 
backward instead of 
forward, the method 
of construction, how- 
^^ ^2: ever, being the same 

(d) Isometric with Axes Reversed. _ ^' " 

Fig. 128, —Isometric Drawings of Wall Built of Blocks. in Cither CaSC. 




ISOMETRIC DRAWING AND SKETCHING 



163 



125. Isometric of a Cylinder. Make a drawing of a cube 
that will just enclose the 
cylinder, then draw the 
ellipse within the rhom- 
bus that represents the 
top of the cube See Fig. 
129. Likewise construct 
the base of the cube, and 
connect the top and the 
base with tangent lines 
as shown in the figure. 

126. Isometric of Screw Threads. In order to save time the 
true forms of screw threads are never shown in isometric draw- 
ings. The conventional method of representing the threads is 




Fig. 129. — Isometric Drawings of Cylinder in DiflEerent 
Positions. 




Fig. 130 



Nut and Bolt with Conventional 
Isometric Thread. 



shown in Fig. 130. To make such a drawing consider the body 
of the bolt as a cylinder and proceed as in § 125, this page. The 
ellipse which represents the base of the cylinder is to he repeated 
in the proper positions to indicate the threads, the distances be- 
tween the ellipses usually being taken equal to the pitch of the 
thread; that is, the distance between the ellipse centers is equal 
to the thread pitch. See " Centers" at j, 2, j, etc., in the figures. 



164 ^ ELEMENTS OF DRAWING ~ 

The internal thread shown in the Nut is similarly constructed. 

127. Hollow Cylinder with a Quarter Section Removed. It is 

very often advisable to show an object with a section removed 
as in Fig. 131. 

This drawing is of a Lathe- Spindle (see Frontispiece, also 
Fig- 147; page 172). To construct such a drawing proceed as in 




Fig. 131. — Isometric of Lathe Spindle 
with Section removed. 

§1125, page 163, to obtain the outline of the cylinder. Next, con- 
sider the hole in the cylinder as a second cylinder and draw in its 
outline. To " take out " the section a plane such as A-B-D-C 
is assumed passed vertically through the axis A-B of the spindle 
and a plane, such as A-E-F-B, is assumed passed horizontally 
through the axis. In this construction note that the centers of 
all ellipses are on the axis A-B and their respective distances 
from the ends of the spindle are measured on this axis. 

128. Offset Construction in Isometric Drawing. It is not 

always necessary to enclose the object completely in a cube or 
rectangle, as described in § 122, page 160, in order to make an 
isometric drawing. See also § 125, page 163. It frequently 
occurs that the isometric lines can be drawn more readily by the 
offset construction as illustrated in Fig. 132, page 165. 



ISOMETRIC DRAWING AND SKETCHING 



165 



129. Isometric Drawing of a Sphere. The isometric drawing 
of a sphere is represented by a circle. To determine the radius of 
this circle, make an isometric drawing of a circle having the same 




Fig. 132. ^Offset Construction. 



diameter as the sphere. The radius of the circle which represents 
the sphere will be equal to one-half the major axis of the ellipse 
which represents the circle. In Fig. 133 is shown a sphere of 
diameter D. The dashed ellipse shown in Fig. 133 (b) is the 





(a) 



(b) 
Fig. 133. — Drawing of a Sphere. 



isometric drawing of a circle having a diameter D. The radius, 
R, of the circle which represents the isometric drawing of the 
sphere is one-half the length of the major axis of the ellipse. 

To draw a half-sphere construct the outline of the sphere as 
described above. Next draw the ellipse which represents a great 



i66 



ELEMENTS OF DRAWING 



circle of the sphere. In Fig. 134 (a) is shown the lower half of a 
sphere and in Fig. 134 (b) is shown the upper half. 




(a) Lower half. (b) Upper half. 

Fig. 134. — Isometric of a Half Sphere, 



Fig- 135. — Isometric of 
One-eighth Sphere. 



To draw one-eighth of a Sphere construct the sphere as de- 
scribed above and next draw the great circles at right angles to 
one another as shown in Fig. 135. 

130. Isometric Drawing of 
Lathe Cap. To get an idea 
of the exact shape of the Lathe 
Cap see Frontispiece and Fig. 
148, page 172. The Cap is a 
combination of a cylinder (see 
§ 125, page 163), a half sphere 
(see § 129, page 165) and of 
V threads (see § 126, page 

163). 

Fig. 136 shows an isometric 
drawing of the Lathe Cap with 
one-quarter section removed. 

131. Size and Numbering 

Fig. 136. -Isometric of Lathe Cap. ^j Skctch ShCCtS. ExercisCS 

in isometric sketching are to be done on small sheets of standard 
letter size (8" X io|") heavy weight isometric-ruled paper (see 
§ 4, page 5), the ruling on one side only. The paper is to be 
punched for standard No. 10 Manila cover. As previously stated, 
one of the disadvantages of making isometric drawings me- 
chanically is due to the frequent necessity of drawing ellipses. 
This, however, is an advantage in free-hand sketching, since the 
ellipse is more easily drawn free-hand than the circle. The chief 




ISOMETRIC DRAWING AND SKETCHING 1 67 

objection to making isometric sketches is due to the difficulty of 
maintaining the thirty-degree angle. This difficulty can be 
entirely overcome by the use of isometric ruled paper, see Fig. i (b) , 
page 5. This paper has, besides the regular vertical and hori- 
zontal ruling of the ordinary cross-section paper, also lines ruled 
at thirty degrees to the horizontal. This ruling insures the proper 
slope to all isometrically horizontal lines and the draftsman needs 
no other instruments than a pencil and measuring rule to make 
isometric drawings oj the most complex nature. 

The order in which free hand isometric sketch sheets are exe- 
cuted will be indicated by Roman numbers beginning with I and 
continuing as far as necessary. For the general system to be 
followed see Appendix A, page 175. 

SET OF FREE-HAND ISOMETRIC EXERCISES. 

132. Sheet I. The purpose of this sheet is to give practice in 
making an Isometric Drawing of a simple object and also to bring 
out some of the elementary principles of Isometric Sketching. 

Before starting to draw, read, and be prepared for examination 
on, paragraphs, as follows: 

Ruled Paper, page 5, §4. — Lead Pencil, page 14, §14. — 
Erasers and Erasures, page 16, § 15. — The Free-hand Pencil 
Line, page 134, §95. — Introductory, page 156, §116. — Prin- 
ciples, page 157, § 117. — Isometric Drawing of a Cube, page 157, 
§118. — Definitions, page 158, §119. — Isometric Drawing of a 
Circle, page 159, § 120. — Size and Numbering of Sketch Sheets, 
page 166, § 131, and for information on the general system to be 
followed see page 175, Appendix A. 

Exercise on Sheet I. 
This exercise con- 
sists of an Isometric 
sketch of Tool Rest 
Support Shde for the 
Lathe, see Fig. 137; 

, -_-, J. . Fig. 137.— Perspective of Tool Rest Support Slide. 

also rrontispiece. 

Specific Instructions for Executing Sheet I. Tack down the 
isometric ruled sheet, stamp in the title-form (see Fig. 93, page 
138) in the lower right-hand corner of sheet, and neatly write with 
ink the wording of the title. 




1 68 



ELEMENTS OF DRAWING 



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ISOMETRIC DRAWING AND SKETCHING 169 

The title of sheet I is Support Slide. 

Do not use a straight-edge in any of this free-hand course as 
this will seriously impair the value of the work. 

Make a pencil perspective sketch of the Support Slide on central 
portion of the sheet, and to about the scale shown in Fig. 138. 
Dimension the sketch, and when the sheet has been cleaned and 
all the lines made clear cut and of the desired weight and con- 
struction, and the work is thoroughly checked, submit it for in- 
spection and approval. Compare this sketch with Fig. 51 (b), 
page 74, and determine in your own mind which ■ conveys the 
necessary information with the fewer lines, also which would be 
the more readily understood by the average person who would 
use drawings. 

133. Sheet n. The purpose of these exercises is to give 
further practice in making Isometric Sketches of simple objects. 

Before starting this exercise, read and be prepared for exami- 
nation on, paragraphs, as follows: 

Approximate Method of making an Isometric Drawing of a 
Circle, page 160, § 121. — Isometric Drawing of a Plane Figure 
composed of Straight and Curved Lines, page 160, §122. — 
Isometric of a Cylinder, page 163, § 125. — Isometric of a Screw 
Thread, page 163, § 126. 

Exercises on Sheet II. The exercises on this sheet consist of 
pencil Isometric Sketches of a Key (see Fig. 139), of a Shim (see 





Fig. 139. — Perspective Fig. 140. — Perspective 

of Key. of Shim. 




Fig. 141.— Perspective 
of Stud. 



Fig. 142. — Perspective of Fiber Fig. 143. — Perspective 

or Steel Washer. of Special Nut. 

Fig. 140), of a Stud (see Fig. 141), of a Washer (see Fig. 142), and 
of a Nut (see Fig. 143), all of these being parts of the Speed Lathe 
as shown on Frontispiece. 



170 



ELEMENTS OF DRAWING 



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ISOMETRIC DRAWING AND SKETCHING 



171 



Specific Instructions. Stamp the title-form (see Fig. 93, page 
138) in lower right-hand corner of sheet and write in ink the 
wording of the title. 

The title of this sheet is Speed Lathe Details. 

Sketch in these parts similar to the way they are shown in Fig. 
144, dimensioning the figures. 

Having perfected the sketches, submit for approval. 

Compare the sketches on this sheet with similar parts sho"\ATi 
in Fig. 82, page 118, and Fig. 97, page 140, and in your own 
mind determine which is the best and quickest method of 
representing these objects. 



134. Sheet III. The purpose of the exercises on this sheet is 
to give practice in making Isometric Sketches directly from the 
object and in dimensioning these sketches, the 
dimensions being obtained by direct measure- 
ment of the object. 

Exercises and Specific Instructions. The 
exercises on this sheet consist of Isometric 
Sketches of a Collar (see Fig. 145) and of a 
Bearing (see Fig. 146) made from direct 
observation of these parts, and all dimensions 
and notes necessary are to be put in, the 
dimensions being obtained by measurements 
made directly on the Collar and the Bearing. 

Stamp in and fill out the title form. 

The title of this sheet is Speed Lathe Details. 

Check the drawing* thoroughly and submit 

r 1 Fig. 146. — Perspective 

for approval. of Bearing. 




Fig. 14s. —Perspective 
of Collar. 




135. Sheet IV. The purpose of this exercise is to give practice 
in making an isometric sketch in ink and in showing an object 
with a quarter section removed, the sketch being on plain paper. 

Before starting to draw, read and be prepared for examination 
on paragraphs as follows : 

Freehand Inked Line, page 136, § 96. — Isometric Drawing of 
a Cube cut by a Plane, page 161, § 123. — Hollow Cylinder with 
a Quarter Section Removed, page 164, § 127. 



172 



ELEMENTS OF DRAWING 



Exercise and Specific Instructions. Tack down a standard 
size sheet of plain paper of good quality to take ink and make an 
Isometric Sketch, in pencil first, of Lathe Spindle (see Fig. 147) 




Fig. 147. — Perspective of Tailstock Spindle. 

similar to Fig. 131, page 164, except the key way is to be shown 
and the sketch dimensioned from the object. The sketch having 

been perfected in pencil, it is to be neatly 

inked in. 

The title of this sheet is Lathe Spindle. 




Fig. 148. —Perspective 
of Lathe Cap. 



136. Sheet V. Make an isometric drawing 
of a Lathe Cap (see Fig. 148), with a quarter 
section removed (see Fig. 136, page 166). 

Before starting to draw, read and be prepared 
for examination on paragraphs as follows : 
Isometric Drawing of a Sphere, page 165, § 129. — Isometric 
Drawing of a Lathe Cap, page 166, § 130. 

Specific Instructions. Stamp in and fill out the title form. 
The title of this sheet is Lathe Cap. 

Make all lines very light until the correct outline is obtained; 

clean the sheet and sketch in the object clear cut and complete. 

Submit the sheet for approval. 

137. Sheet VI. An isometric sketch is to 
be made of a Lathe Shelf Bracket (see Fig. 
149), showing the object in two different posi- 
tions, as illustrated in Fig. 150, page 173. This 
sketch is to be finished up in pencil and then 
inked in freehand. 

Before starting this drawing, read, and be 
prepared for examination on, paragraphs, as ^ ^ 
follows : 

Isometric Drawing of a Wall, page 162, 




49. — Perspective of 
Shelf Bracket. 



124. — Offset con- 



struction in Isometric Drawing, page 164, 
The title of this sheet is Shelf Bracket. 



128. 



ISOMETRIC DRAWING AND SKETCHING 



173 




174 



ELEMENTS OF DRAWING 



138. Examination on Chapter V. As a final examination on 
this chapter make an Isometric Drawing of Tool Rest Support 
(see Fig. 151) or of any other parts of the Lathe or of parts of 
any other machine assigned, on plain or ruled paper, and in 
pencil or ink as directed. Also study the subject matter con- 
tained in § 116, page 156, to § 132, page 167, in preparation for 
examination. 




Fig. 151. — Perspective of Tool Rest Support. 



APPENDIX A. 



DRAWING ROOM SYSTEM. 

139. Commercial Drawing Rooms. In practically all com- 
mercial drawing rooms work is carried on under some fixed 
system, the nature of which depends upon the character and 
scope of the work to be accomplished. Such systems usually 
require that drawings be made to certain standard sizes; that 
a certain title form providing for specific information be used; 
that certain styles of lettering be used; that certain conventions 
and abbreviations be used, and so forth. The value of doing 
the work of this course under an efficient system can therefore 
be readily understood, and it is expected that either the system 
as outlined below or a system provided by the instructor will 
be followed. 

(a) General Method of Procedure. Having secured instru- 
ments and supplies (see § 2, page 2) proceed with the drawing 
course beginning with the set of Freehand Lettering Exercises 
as outlined in § 38, page 44 to § 52. Next take up the set 
of Mechanical Drawing Exercises as outlined in § 79, page 116, 
to § 91. Then take up the set of Freehand Drawing Exercises 
as outHned in § 100, page 139, to §116, and finally take up the set 
of Isometric Freehand Sketching Exercises as outHned in § 132, 
page 167, to § 139. 

In working up the exfercises on each sheet or drawing proceed 
in the following manner: 

1. Read all text matter assigned and be prepared for ex- 
amination on same. 

2. Tack down the sheet or drawing (see § 73, page 107) and 
where necessary draw in the border Une (see § 72, page 106). 

3. Put the title form in the lower right-hand corner. Write 
in with ink the wording of the title form as far as possible. 

4. Proceed with the actual drawing as instructed in the text. 
NOTE. Satisfactory progress can be made only when the 

beginner learns to criticise his own work intelHgently as it 

17s 



176 APPENDIX 

proceeds and when he forms the habit of making at once any 
changes found necessary from his own criticism or suggested 
by the instructor. 

Before requesting the instructor to finally inspect a piece of work, 
the student must check every exercise and bring the work as a whole 
up to the highest standard of perfection of which he is capable. 

When the exercises appear satisfactory to the instructor, he 
signs his name (or initials) in the title form after the word " IN- 
SPECTED:' The student is then to write with ink the DA TE 
FINISHED and the TOTAL ACTUAL HO URS expended on 
the work; it is then deposited in some prescribed place in order 
that the instructor may further check it if thought best. 

If deficiencies are found in checking the work, it will be returned 
once for the student to make the corrections and changes indi- 
cated. Exceptional care must be taken, when making changes 
to avoid spoiling the work. 

Work not neatly and accurately corrected will not be approved. 

All changes and corrections indicated must be made at the 
earliest possible date and the corrected work immediately 
returned to the proper place by the student. 

// the quality of work done on any part of the sheet, drawing, 
tracing, or plate is unsatisfactory and cannot be brought to the 
required standard of perfection by the student, it must be repeated 
until all requirements are met. 

When inspected work is not returned to the student within a 
reasonable length of time, this indicates that the instructor in 
further checking has found no serious deficiencies and has given 
the work final approval. 

In no case is a student to trace a drawing, make a drawing from 
a sketch, or do any advanced work which depends upon work previ- 
ously done, unless the original has been finally approved by the 
proper instructor. 

(b) Sizes of Drawings. All lettering, sketching and computing 
work is to be done on " sheets " measuring 8" by io|". (See 
page 44, § 37; page 139, § 99; page 166, § 131.) All mechanical 
drawing is to be done on paper or tracing cloth, measuring 12'' 
by 18", this size to be designated by a Capital C. (See page 
106, § 72.) 



APPENDIX 177 

(c) Position of Sheet or Drawing on the Board. All sheets 
and drawings are to be tacked down with the short dimensions 
to the sides unless other instructions are given. The punched 
holes of the " sheets " should be at the top and the punched 
holes of the " drawings " on the left-hand side. (See page 107, 

§ 73-) 

(d) Border Lines. No border Hne is to be used on small 
" sheets," but on " drawings " the border line shown in Fig. 73, 
page 106, is to be used. 

(e) Numbering and Lettering of Sheets and Drawings. 
Sheets of Lettering will be designated by capital letters, begin- 
ning with A. Sheets of Freehand Drawing will be designated 
by Arabic numbers beginning with /. Sheets of Isometric 
Freehand Drawing will be designated by Roman numbers 
beginning with I. Mechanical Drawings will be designated by 
the word " DRAWING," followed by the capital Letter C, which 
is then followed by the number of the drawing — the first draw- 
ing being loi, thus DRAWING C — loi. 

(/■) Title Form and its Location. On small " sheets " of 
Lettering, Sketching, and Computing the small Title Form as 
shown in Fig. 93, page 138, is to be used. For Mechanical 
Drawings of the 12" by 18" size the large Title Form as shown in 
Fig. 69, page 100, is to be used. The wording, however, is to be 
appropriately modified. 

On sheets the title form is to be located in the lower right-hand 
corner. On drawings with border fines the title form is to be 
located in the lower right-hand corner just within the border 
lines, imless other instructions are given. 

(g) Bill of Material and its Location. On drawings requiring 
a bill of material the Bill of Material form shown in Fig. 70, 
page 10 1, is to be used and is to be located just above the title 
form, unless other instructions are given. 

(h) Style of Lettering. The Freehand Slant Gothic alphabet 
is to be used. (See Fig. 42, page 57; Fig. 43, page 61; § 44, 
page 62; § 45, page 68). 

(i) Conventions and Abbreviations as given in the text 
matter are to be used whenever necessary, and uniformity in 
this regard is to be strictly maintained. 



INDEX. 



A. 



A, description of the letter, p. 47, § 3S; p. 63, § 47. 
Abbreviation "&," description of, p. 54, § 41. 

for "feet," p. 95, § 62. 

for "radius," p. 97, § 62. 

for materials, p. 103, § 67. 
Ability to letter, p. 34, § 31. 
Acme thread, p. 89, § 59. 

Adjacent part conventionally shown, p. 89, § 59. 
Alphabet, Gothic (see also Letters, description of), p. 34, § 31. 
Angles, dimensioning of, p. 97, § 62. 
Appendix A, p. 175, § 139. 
Architect's scale, p. 29, § 27. 
Area, cross-sectioning an, p. 82, § 55. 
Arrangement of views, p. 75, § 53. 

and number of views, p. 83, § 56. 
Arrowheads, p. 77, § 54. 

position of, p. 95, § 62. 
Arrows, direction, in lettering, p. 38, § 34. 

A. S. M. E. standard screws, p. 126, § 84. 
Assembly drawings, p. 86, § 58. 

Axes, isometric, p. 158, § 119. 

isometric reversed, p. 162, § 124. 

B. 

B, description of the letter, p. 53, § 41; p. 64, § 47. 
Ball-pointed pen, p. 3, § 2; p. 19, § 19. 

Bearing conventionally shown, p. 87, § 59. 

Bill of material, general description of, p. loi, § 67. 

used in this work, p. loi, § 67. 
Blocking or laying out a drawing, p. 84, § 56; p. 93, § 61. 
Blotter, p. 4, § 2; p. 33, § 30. 
use of a, p. Ill, § 75. 
Blot on a drawing, to remove, p. in, § 75. 
Blue print paper, p. 2, § 2; p. 6, § 7. 

changes on, p. 116, § 78. 
method of making, p. 7, § 7. 
method of using, p. 116, § 78. 
Blue printing machines, p. 116, § 78. 
Blue print, exercise in making a, p. 121, § 81. 

frame, p. 116, § 78. 
Board, drawing, p. 2, § 2; p. 7, § 8. 
use of, p. 107, § 73. 
Bolts, table of U. S. Standard, p. 127, § 84. 
Border lines, layout of, in this work, p. 106, § 72. 

use of, on a drawing, p. 106, § 72. 
Bottle holder, p. 112, § 75. 
Bow dividers, p. 3, § 2; p. 27, § 24. 
pencils, p. 3, § 2; p. 27, § 25. 
design of, p. 27, § 25. 
, selection of, p. 27, § 25. 

179 



l8o INDEX 

Bow pencils, to test, p. 28, § 25. 
use of, p. 28, § 25. 
pens, p. 3, § 2; p. 28, § 26. 
to test, p. 29, § 26. 
use of, p. 28, § 26. 
Broken lines, conventional, p. 76, § 54; p. 89, § 59. 
Broken sections, conventional, p. 87, § 59. 
Building up a drawing or sketch, p. 137, § 97. 

C. 

C, description of the letter, p. 52, § 41; p. 64, § 47. 
Calipers, machinists', p. 4, § 2; p. 32, § 29. 
inside, p. 32, § 29. 
outside, p. 32, § 29. 
use of, p. 32, § 29. 
Cap screws, p. 128, § 84. 
Capital letters, characteristics of curved, p, 51, § 41. 

characteristics of straight line, p. 44, § 38. 
description of, p. 44, § 38; p. 51, § 41. 

detailed description of each letter (see Letters, description of). 
spacing of, p. 40, § 35. 
Capital and small letters, spacing between, p. 42, § 35. 
Carbonate of soda, p. 4, § 2; p. 116, § 78. 
Care of instruments, p. i, § i. 
Center lines, p. 78, § 54. 

in lettering, p. 37, § 34- 
on a drawing, p. 108, § 74. 
Center line, symbol for, p. 78, § 54. 
Changes on a drawing, p. 99, § 65. 

blue prints, p. 116, § 78. 
tracing, p. 17, § iS- 
Checking drawings, p. 113, § 76. 
Checking, how to proceed in, p. 113, § 76. 
Choice of dimensions, p. 95, § 62. 

a scale, p. 93, § 61. 
Circle, dimensioning a, p. 97, § 62. 
Circle, isometric drawing of, p. 159, § 120. 
approximate method, p. 160, § 121. 
Cleaning drawings, p. 16, § 15. 
Cloth, tracing, p. 2, § 2; p. 6, § 6. 
Colored inks, p. 18, § 18. 
Compasses, p. 3, § 2; p. 23, § 22. 
design of, p. 23, § 22. 
use of, p. 25, § 22. 
Compass, head-joint design, p. 23, § 22. ' 
socket-joint design, p. 24, § 22. 
Conventions, p. 87, § 59. 

common, p. 88, Fig. 65. 
Conventional drawing of bearing, p. 87, § 59. 
drilled hole, p. 90, § 59. 
hollow part, p. 87, § 59. 
lines, p. 76, § 54; p. 89, § 59. 
methods, p. 87, § 59. 
method of showing an adjacent part, p. 89, § 59. 

screw threads in isometric, p. 163, § 126. 
method of showing timber, p. 87, § 59. 
National Acme thread, p. 89, § 59 
screw thread, p. 72, § 52; p. 89, § 59. 
sectioning, p. 81, § 55. 
shaft, p. 87, § 59. 
square thread, p. 89, § 59. 



INDEX l8l 

Conventional steel shape, p. 90, § 59. 
tapped hole, p. 90, § 59. 
V thread, p. 89, § 59. 
Construction of lines, p. 76, § 54. 
Cored holes, p. 97, § 62. 
Covers, Manila, p. 4, § 2. 
Cross sectioning, p. 82, § 55. 

conventional, p. 8r, § 55; p. 90, § 59. 
instrument for, p. 82, Fig. 64. 
Cross section, p. 79, § 55; p. 83, § 55. 

paper, p. 2, § 2; p. 5, § 4- 
Crow-quill pen, p. 3, § 2; p. 19, § 19. 
Cube, isometric drawing of, p. 157, § 118. 

cut by a plane, p. 161, § 123. 
Curves, French or irregular, p. 2, § 2; p. 13, § 12. 

use of, p. i5, § 12. 
Cyhnder, hollow, shown in isometric, p. 164, § 127. 
isometric of, p. 163, § 125. 

D. 

D, description of the letter, p. 52, § 41; p. 63, § 47. 
Definitions, isometric drawings, p. 158, § 119. 

Description of capital letters {see also Letters, description of), p. 44, § 38; p. 51, § 41. 
numerals, {see detailed description of), 
small letters, {see also Letters, description of), p. 60, § 47. 
Detail drawings, p. 85, § 57. 

paper, p. 5, § 3. 
Dimensioning, p. 34, § 31; p. 94, § 62. 
a circle, p. 97, § 62. 
a radius, p. 97, § 62. 
a threaded piece, p. 97, § 62. 
angles, p. 97, § 62. 
cored holes, p. 97, § 62. 

drawings and sketches, p. 94, § 62; p. 132, § 93. 
fillets, p. 97, § 62. 
of holes, p. 89, § 59. 
refinement in, p. 95, § 62. 
rules for, p. 94, § 62. 
Dimension hnes, p. 77, § 54. 

nvunbers, p. 95, § 62. 
Dimensions, purpose of, p. 94, § 62. 
checking, p. 95, § 62. 
choice of, p. 95, § 62. 
limits in, p. 95, § 62. 
location of, p. 96, § 62. 
not to scale, p. 95, § 62. 
nimabers, expressing, p. 95, § 62. 
on model letters, p. 38, § 34. 
overall, p. 96, § 62. 
related, p. 96, § 62. 
Dimensioning of fillets, p. 97, § 62. 

tapped holes, p. 97, § 62. 
tapers, p. 97, § 62. 
rough castings, p. 95, § 62. 
working drawings, p. 94, § 62. 
Direction arrows in lettering, p. 38, § 34. 
Distance between letters, p. 39, § 35. 
Dividers, p. 3. § 3; P- 26, § 23. 

bow, p. 3, § 2; p. 27, § 24. 
machinists', p. 4, § 2; p. 33, § 29. 

use of, p. Z2>, § 29; P- 26, § 23. 



l82 INDEX 

Drawing, an assembly, p. 86, § 58. 

arrangement and number of views on, p. 83, § 56. 
blocking out a, p. 84, § 56; p. 93, § 61. 
boards, p. 2, § 2; p. 7, § 8. * 

care of, p. 8, § 8. 
design of, p. 7, § 8. 
use of, p. 107, § 73. 
border line for a, p. 106, § 72. 
building up an assembly, p. 86, § 58. 

a detail, p. 137, § 97. 
care of, p. 15, § 14. 
changes on a, p. 99, § 65. 
checking a, p. 113, § 76. 
cleaning a, p. 16, § 15. 
conventional, p. 87, § 59. 
definition in isometric, p. 158, § 119. 
detail, p. 85, § 57. 

dimensioning a working, p. 94, § 62. 
exercises in mechanical, p. 116, § 79. 
free-hand, p. 139, § 100. 
isometric free-hand, p. 167, § 132. 
ink, p. 3, § 2; p. 18, § 18; p. no, § 75. 

care of, p. 18, § 18. 

selection of, p. 18, § 18. 

use of, p. no, § 75. 
instruments, p. 3, § 2. 
isometric, p. 156, § 116. 
isometric, of a cube, p. 157, § 118. 
paper, p. 2, § 2; p. 4, § 3. 
paper, selection of, p. 4, § 3. 

part or reference number on a, p. 90, § 57; p. 104, § 
pencils p. 3, § 2; p. 14, § 14. 
pens, unsatisfatory results with, p. no, § 75. 
perspective, p. 71, § 52. 

position in which to tack down, p. 108, § 73. ^ 

mechanical. Chapter III, p. 71, § 52. 
notes on a, p. 73, § 52; p. 97, § 63. 
numbering and size of, in this work, p. 103, § 68. 
record on a, p. 98, § 65. 
recording patterns on a, p. 104, § 70. 
requirements of a, p. 72, § 52. 
room system. Appendix A, p. 175, § 139. 
scale of a, p. 93, § 61. 
selection of, p. 14, § 14. 

size and numbering of, in this work, p. 103, § 68. 
size and numbering of, p. 103, § 68. 
symbols on a, p. 72, § 52. 
time keeping in, p. 105, § 71. 
title-form on a, p. 100, § 66. 
to fasten on board, p. 107, § 73. 
to ink a, p. no, § 75. 
to make a pencil, p. 108, § 74. 
to protect a, p. 112, § 75. 
to scale, p. 90, § 60. 
to sharpen, p. 15, § 14. 
Drilled hole, conventional, p. 90, § 59. 



E, description of the letter, p, 45 § 38; p. 64, §47. 
Eight, description of the numeral, p. 59, § 44. 
Element of adjacency, definition of, p. 40, § 35. 



INDEX 183 



Elevation, front and side, p. 75, § 53- 
Ellipse, the sloping, p. 50, § 40. 
Engineer's scale, p. 29, § 27. 
Erasers, p. 3, § 2; p. 16, § 15. 
care of, p. 17, § 15. 
selection of, p. 16, § 15. 
use of, p. 16, § 15. 
Erasing shield, p. 3, § 2; p. 17, § 16. 
Erasures, how to make, p. 17, § 15. 

on tracing cloth, p. 115, § 77. 
Examination in free-hand drawing, p. 154, § 115. 

isometric free-hand drawing, p. 174, § 138. 
lettering, free-hand, p. 69, § 51. 
mechanical drawing, p. 130, § 90. 
Exercises in free-hand drawing, p. 139, § 100, etc. 

isometric drawing, p. 167, § 132, etc. 
lettering, p. 44, § 38, etc. 
mechanical drawing, p. 116, § 79, etc. 
numerals, p. 60, § 45, etc. 



F, description of the letter, p. 45, § 38; p. 66, § 47. 
Fastening the paper or tracing cloth on the board, p. 107, § 73. 
Fasteners, paper, p. 4, § 2. 

Faulty lines, p. iii, § 75. 

Feet, abbreviation for, p. 95, § 62. 

Fillets, dimensioning, p. 97, § 62. 

Finish mark, p. 98, § 64. 

Finished line, p. 78, § 54. 

Finish of a surface, p. 98, § 64. 

Fit, force, p. 95, § 62. 

Five, description of the nimieral, p. 59, § 44. 

Flat scale, p. 29, § 27. 

Force fit, p. 95, § 62. 

Formula for making blue-print paper, p. 7, § 7. 

Four, description of the numeral, p. 58, § 44. 

Fractions, slope of, p. 60, § 45. 

how to print, p. 60, § 45. . 

Free-hand copies of working sketches, p. 131, § 92. 

drawing exercises, set of, p. 139, § 100, etc., see also Chapter IV, Table 
of Contents, 
examination in, p. 154, § 115. 

inked lines, p. 136, § 96. 

isometric exercises, set of, p. 167, § 132, see also Chapter V, Table of 
Contents, 
examination in, p. 174, § 138. 

lines, to draw, p. 134, § 95. 

penciled lines, p. 134, § 95. 

sketching, p. 132, § 93. 

sketches made directly from objects, p. 133, § 93. 

working sketches, p. 131, Chapter IV. 
French curves, p. 2, § 2; p. 13, § 12. 
Front elevation, p. 75, § 53. 

G. 

G, description of the letter, p. 52, § 41; p. 64, § 47. 

Gothic alphabet {see also Letters, description of), p. 34, § 31. 
Guide lines in lettering, p. 37, § 34. 



1 84 INDEX 



H. 

H, description of the letter, p. 45, § 38; p. 65, § 47. 
Headings and titles, design of, p. 69, § 49. 
Headstofe, assembly of lathe, Frontispiece. 
Holder, bottle, p. 112, § 75. 

pen, p. 3, § 2; p. 20, § 20. 
Hole, drilled or tapped, p. go, § 59. 

cored, p. 97, § 62. 
Holes, dimensioning, p. 89, § 59. 

tapped, dimensioning, p. 97, § 62. 
Hollow part, conventional, p. 87, § 59. 
Horizontal plane of projection, p. 73, § 53. 



I, description of the letter, p. 45, § 38; p. 65, § 47. 
Inches, symbol for, p. 95, § 62. 
Inclined lines of lettering, p. 69, § 49. 
Ink, bottle holder, p. 112, § 75. 
colored, p. 18, § 18. 
drawing, p. 3, § 2; p. 18, § 18; p. no, § 75. 

requirements of, p. 18, § 18. 
quantity to carry on pen, p. in, § 75; p. 137, § 96. 
too little on pen, p. in, § 75. 
too much on pen, p. in, § 75. 
Inked lines, blotting, p. in, § 75. 
free-hand, p. 136, § 96. 
which meet or intersect, p. ni, § 75. 
Inking a drawing, p. 21, § 21; p. no, § 75. ■ 

order of, p. 113, § 75. 
Instrument cleaner, p. 4, § 2; p. 33, § 30. 
Inside calipers, p. 32, § 39. 
Inking exercises, in free-hand drawing, p. 154, §§ 112-114. 

free-hand lettering, p. 56, § 43; p. 60, § 46; p. 67, § i 
isometric free-hand drawing, p. 171, § 135 and § 137. 
mechanical drawing, p. no, § 75. 
Instruments, care of, p. i, § i. 
drawing, p. 3,§ 2. 
list of, p. 2, § 2. 
quality of, p. i, § i. 
rag for cleaning, p. 4, § 2; p. 33, § 30. 
selection of, p. i. 
Intersecting inked lines, p. in, § 75. 
Invisible line, p. 76, § 54. 1 

threads, p. 89, § 59. 
Irregular curves, p. 2, § 2; p. 13, § 12. 

selection of, p. 13, § 12. 
use of, p. 13, § 12. 
Isometrics, p. 156, § 116. 
Isometric axes, p. 158, § 119. 

reversed, p. 102, § 124. 
conventional thread, p. 163, § 126. 
drawing of a lathe cap, p. 166, § 130. 
plane figure, p. 160, § 122. 
sphere, p. 165, § 129. 
wall, p. 162, § 124. 
Isometric drawing, offset construction in, p. 164, § 128. 
advantages of, p. 156, § 116. 
and sketching, p. 156, Chapter V. 
definitions, p. 158, § 119. 



INDEX 



185 



Isometric drawing, disadvantages of, p. 157, § 116. 

approximate method, p. 160, § 121. 

circle, p. 159, § 120. 

cube, p. 157, § 118. 

cube cut by a plane, p. 161, § 123. 

exercises, set of, p. 167, § 132 {see also Chapter V, Table of 
Contents) . 

principles of, p. 157, § 117. 
line, p. 158, § 119. 
measurements, p. 159, § 119. 
of a cylinder, p. 163, § 125. 
of a half sphere, p. 165, § 129. 

of a hollow cylinder with section removed, p. 164, § 127. 
of one-eighth sphere, p. 166, § 129. 
of screw threads, p. 163, § 126. 
origin, p. 158, § 119. 
position, p. 159, § 120. 
projection plane, p. 157, § 117. 
sketching, examination in, p. 174, § 138. 
sketching sheets, p. 166, § 131. 
Isometrics, exercises in, p. 167, § 132, etc. 
principles of, p. 157, § 117. 



J. 

/, description of the letter, p. 53, § 41; p. 66, § 47. 

K. 

K, description of the letter, p. 47, § 38; p. 65, § 47. 
Key or chart for spacing, p. 43, § 35. 

L. 

L, description of the letter, p. 45, § 38; p. 65, § 47. 
Lathe, speed, perspective drawing of, Frontispiece. 
Laying out or blocking out a drawing, p. 84, § 56. 
Lead pencil, p. 3, § 2; p. 14, § i4- 
care of, p. 15, § 14. 
how to sharpen, p. 15, § 14. 
selection of, p. 14, § 14. 
Leader, definition of, p. 97, § 62. 
Lengthening or extension bar, p. 23, § 22. 
Letter, abihty to, p. 34, § 31. 
Lettering, p. 34, § 31. Chapter II. 

and size of letter sheets, p. 44, § 37. 

critical study of, p. 36, § 32. 

exercises in, p. 44, § 38 {see also Chapter II, Table of Contents). 

in bill of material, p. 102, § 67. 

inclined lines of p. 69, § 49. 

in title form, p. 100, § 66. 

on working drawings, p. 34, § 31. 

pens, requirements of, p. 19, § 19. 
to break in, p. 20, § 19. 

systematic method of, p. 44, § 36. 
Letter A, capital, description of, 

a, small, 

B, capital, 

b, small, 

C, capital, 

c, small, 

D, capital, 

d, small, 



p- 


4/, 8 
63, § 


47- 


p- 
p- 


53, § 
64, § 


41. 
47- 


p- 
p- 


52, § 
64, § 


41. 
47. 


p- 
p- 


52, § 
63, § 


41. 
47. 



i86 



INDEX 



Letter E, capital, description of, p. 45, § 38. 

e, small, " " p. 64, § 47. 

F, capital, " " p. 45, § 38. 

f, small, " " p. 66, § 47- 

G, capital, " " p. 52, § 41. 

g, small, " " p. 64, § 47. 
H, capital, " " p. 45, § 38. 
h, small, " " p. 65, § 47. 
I, capital, " " p. 45, § 38. 
i, small, " " p. 65, § 47. 
J, capital, " " p. 53, § 4i- 
j, small, " " p. 66, § 47. 

, K, capital, " " p. 47, § 38. 

k, small, " " p. 65, § 47. 

■ L, capital, " " p. 45, § 38. 

1, small, " " p. 6s, § 47. 

M, capital, " " p. 46, § 38. 

m, small, " " p. 65, § 47. 

N, capital, " " p. 46, § 38. 

n, small, " " p. 64, § 47. 

O, capital, " " p. 51, § 41. 

o, small, " " p. 63, § 47. 

P, capital, " " p. 5s, § 41- 

p, small, " " p. 64, § 47. 

Q, capital, " " p. 52, § 41. 

q, small, " " p. 64, § 47. 

R, capital, " " p. 53, § 41- 

r, small, " " p. 65, § 47. 

5, capital, " " p. 53, § 41, 
s„ small, " " p. 66, § 47. 
T, capital, » " p. 45, §38- 
t, small, " " p. 66, § 47. 
U, capital, " " p. 52, § 41. 
u, small, " " p. 65, § 47. 
V, capital, " " p. 46, § 38. 
V, small, " " p. 67, § 47. 
W, capital, " " p. 47, § 38. 
w, small, " " p. 67, § 47. 
X, capital, " " p. 46, § 38. 
X, small, " " p. 67, § 47. 
Y, capital, " " p. 46, § 38. 
y, small, " " p. 65, § 47. 
Z, capital, " " p., 47, § 38. 
z, small, " " p. 67, § 47. 

6, the symbol, " " p. 54, § 41. 

Letters, capital or upper-case {see Letters, General Description of), 
center lines for, p. 37, § 34. 
description of model, p. 37, § 34. 
distance between, p. 39, § 35. 
general appearance of, p. 35, § 32. 
general description of model, p. 37, §34; p. 44, § 38; p. 51, § 41; p. 58, 

§ 44; P- 60, § 47- 
grouping of, p. 35, § 32. 
guide lines for, p. 37, § 34. 
pattern, p. 105, § 70. 
slope of, p. 36, § 33. 
slope of, in this work, p. 37, § 33. 
small, p. 42, § 35. 

small or lower-case (^ee Letter, Description of), 
spacing key or chart for, p. 43, § 35. 
spacing of, p. 39, § 35. 

capital, p. 40, § 35. 
stem of, defined, p. 37, § 34. 



INDEX 187 

Lettering, examination in, p. 69, § 51. 

inclined, Knes of, p. 69, § 49. 
in title form, p. 100, § 66. 
study of, p. 34, § 32. 
system of strokes in, p. 38, § 34. 
Limits, dimension, p. 95, § 62. 
Line, an isometric, p. 158, § 119. 

a non-isometric, p. 158, § 119. 

a " clear-cut," or finished, p. 78, § 54. 

to draw an inked, p. 11 1, § 75; p. 136, § 96. 

to draw a pencil, p. 134, § 95. 
Liner, section, p. 82, § 55. 
Lines, border, p. 106, § 72. 

center, p. 78, § 54. 

construction of, p. 76, § 54. 

conventional, p. 76, § 54; p. 89, § 59. 

dimension, p. 77, § 54. 

faulty, p. Ill, § 75. 

finished, p. 78, § 54. 

free-hand inked, p. 136, § 96. 

free-hand penciled, p. 135, § 95. 

intersecting inked, p. iii, § 75. 

invisible, p. 76, § 54. 

on tracing cloth, p. 115, § 77. 

reference, p. 77, § 54. 

section, p. 77, § 54. 

to draw free-hand, p. 134, § 95. 

to draw finished, p. 78, § 54. 

to draw parallel, p. 13, § 11. 

to draw perpendicular, p. 12, § 11. 

visible, p. 76, § 54. 

" weight " of, p. 76, § 54. 
List of instruments and supplies, p. 2, § 2. 
Longitudinal section, p. 79, § 55. 
Lower-case or small letters (see also Letters, Description of), p. 60, § 47. 

M. 

M, description of the letter, p. 46, § 38; p. 65, § 47. 
Machine screws, p. 126, § 84. 
Machinist's calipers, p. 4, § 2; p. 32, § 29. 
dividers, p. 4, § 2; p. 33, § 29. 

selection of, p. 32, § 29. 
selection of, p. 32, § 29. 
use of, pp. 32 and 33, § 29. 
use of, p. 33, § 29. 
scale, p. 4, § 2; p. 32, § 29. 
Manila covers, p. 4, § 2. 
Materials, conventions for, p. 81, § 55. 

abbreviations for, p. 103, § 67. 
bill of, p. loi, § 67. 
indicated by numbers, p. 81, § 55. 
Measurements, p. 30, § 27. 

in isometric drawing, p. 159, § 119. 
Mechanical drawing. Chapter III, p. 71, § 52. 

examination in, p. 130, § 90. 
principles underlying, p. 71, § 52. 

set of exercises in, p. 116, § 79 (see also Chapter III, Table 
of Contents). 
Memory, sketching from, p. 134, § 94. 

Method of drawing angles with triangles and T-square, p. 12, § 11. 
parallel lines, p. 13, § 11. 



i88 



INDEX 



Micrometer, p. 33, § 29. 

Model Letters, general description of, p. 37, § 34. 



N. 

A'', description of the letter, p. 46, § 38; p. 64, § 47. 

National acme thread, p. 89, § 59. 

Naught, the numeral, description of, p. 58, § 44. 

Needle point for instruments, p. 24, § 22. 

Nine, description of the numeral, p. 58, § 44. 

Non-isometric lines, p. 158, § iig. 

Notes on a drawing, p. 73, § 52; p. 97, § 63. 

style of lettering for, p. 98, § 63. 
Number and arrangement of views, p. 83, § 56. 

reference or part, p. 90, § 59; p. 104, § 69. 

used to indicate materials, p. 81, § 55. 
Numbering and size of sheets, p. 139, § 99; p. 166, § 131. 

of drawings, p. 103, § 68. 
Numbers {see Numerals, description of), p. 37, § 34. 
Nximeral i, description of, same as capital I, p. 45, § 

2, 

3, 

4, 

5, 

6, 

7, 

8, 

9, _ 

naught, description of, p. 58, § 44. 
Numerals, exercise in making, p. 60, § 45. 
spacing of, p. 42, § 35. 



p- 


59, 


§44- 


p- 


59, 


§44- 


p- 


58, 


§44. 


p- 


59, 


§44- 


p- 


59, 


§44- 


p- 


58, 


§44- 


p- 


59, 


§44- 


p- 


58, 


§44- 



0. 

O, description of the letter, p. 51, § 41; p. 63, § 47. 

Objects, sketches of, p. 132, § 93. 

Offset construction in isometric drawing, p. 164, § 12J 

Operation sheets, p. 85, § 57. 

Order of inking a drawing, p. 113, § 75. 

checking a drawing, p. 113, § 76. 

penciling a drawing, p. 109, § 74. 
Ordinary pens, p. 3, § 2; p. 18, § 19. 
care of, p. 19, § 19. 
selection of, p. 19, § 19. 
use of, p. 137, § 95. 
Origin, isometric, p. 158, § 119. 
Orthographic projection, p. 73, § 53. 
Outside calipers, p. 32, § 29. 
Overall dimensions, p. 96, § 62. 



P, description of the letter, p. 53, § 41; p. 64, § 47. 
Paper, blue print, p. 2, § 2; p. 6, § 7; p. 116, § 78. 

cross section ruled, p. 2, § 2; p. 5, § 4. 

drawing, p. 2, § 2; p. 4, § 3. 

fasteners, p. 4, § 2. 

isometric ruled, p. 2, § 2; p. 5, § 4. 

ruled, p. 2, § 2; p. 5, § 4. 

to fasten on drawing board, p. 107, § 73. 

tracing, p. 6, § 5. 

Whatman's, p. 5, § 3. 



INDEX i8q 



Parallel lines, method of drawing, p. 13, § 11. 
Part or reference number, p. 90, § 59; p. 104, § 69. 
Part numbers in bill of materials, p. 102, § 67. 
Parts, detailed on a single sheet, p. 85, § 57. 

grouping of, on a single sheet, p. 85, § 57. 
standard, p. 103 § 67; p. 26, § 84. 
Pattern letters on a drawing, p. 105, § 70. 
Pattern maker's rule, p. 92, § 60. 
Pattern numbers, p. 105, § 70. 

in a bill of material, p. 102, § 67. 
Patterns, recording on a drawing, p. 104, § 70. 
Pen, quantity of ink to carry on a, p. 137, § 96. 
Pencil, bow, p. 3, § 2; p. 27, § 25. 

drawing, method of making a, p. 108, § 74. 

eraser, p. 3, § 2; p. 16, § 15. 

lead, p. 3, § 2; p. 14, § 14. 

lines, free-hand, p. 134, § 95. 

pointer or sharpener, p. 3, § 2; p. 14, § 13. 

sharpener or pointer, p. 14, § 13. 

sketching, p. 134, § 95. 

to form a chiseled edge on a, p. 16, § 14. 

cone point on a, p. 15, § 14. 
to sharpen a, p. 15, § 14. 
Penciling, order in which to do, p. 109, § 74. 
Penholders, p. 3, § 2; p. 20, § 20. 
Pens, ball-pointed, p. 3, § 2; p. 19, § 19. 
bow, p. 3, § 2; p. 28, § 26. 
crow-quill, p. 3, § 2; p. 19, § 19. 
for lettering, p. 19, § 19. 
ordinary, p. 3, § 2; p. 18, § 19. 
ruHng or drawing, p. 3, § 2; p. 20, § 21. 
styles of, p. 18, § 19. 
to adjust the ruling, p. 20, § 21. 
to clean the ruhng, p. 22, § 21. 
to fill the ruling, p. 21, § 21. 
to sharpen the ruling, p. 22, § 21. 
to test, the ruling, p. 23, § 21. 
use of the ruling, p. 21, § 21. 
wiper for, p. 33, § 30. 
Pen-wiper, p. 4, § 2; p. 33, § 30. 
Perspective drawing, p. 71, § 52. 
Plan view, p. 75, § 53. 

Plane figure, isometric drawing of a, p. 160, § 122. 
Planes of projection, p. 73, § 53. 
Position, isometric, p. 159, § 120. 
Principles of mechanical drawing, p. 71, § 52. 
isometric drawing, p. 157, § 117. 
Problems {see Exercises) . 
Projecting rays, p. 73, § 53. 
Projection, p. 73, § 53- 

isometric, p. 157, § 117. 
orthographic, p. 73, § 53. 
planes of, p. 73, § 53. 
third angle, p. 74, § 53; p. 84, § 56. 
Proportioning by eye, p. 133, § 93. 
Protractors, p. 4, § 2; p. 31, § 28. 
use of, p. 31, § 28. 

Q. 

Q, description of the letter, p. 52, § 41; p. 64, § 47. 
Quarter-section view, p. 83, § 55. 



igo INDEX 



R. 

R, description of the letter, p. 53, § 41; p. 65, § 47. 
Radius, dimensioning a, p. 97, § 62. 

symbol or abbreviations for, p. 97, § 62. 
Rag, instrument, p. 4, § 2; p. 33, § 30. 
Rays, projection, p. 73, § S3- 
Record forms and titles, p. 98, § 65. 

kept on a drawing, p. 98, § 65. 
Recording patterns on a drawing, p. 104, § 70. 
Reference fines, p. 77, § 54. 

or part numbers, p. 90, § 59; p. 104, § 6g. 
Reversed axes, isometric, p. 162, § 124. 
Rhombus (or rhomb), footnote, p. 158. 
Ruled paper, p. 2, § 2; p. 5, § 4. 

care and use of, p. 5, § 4. 
Rule or scale, p. 3, § 2; p. 29, § 27; p. 32, § 29. 
shrink, p. 92, § 60. 
special, p. 92, § 60. 
Rules for dimensioning, p. 94, § 62. 
Ruhng or drawing pens, p. 3, § 2; p. 20, § 21. 
care of, p. 22, § 21. 
design of, p. 20, § 21. 
to adjust, p. 20, § 21. 
to clean, p. 22, § 21. 
to fill, p. 21, § 21. 
to sharpen, p. 22, § 21. 
to test, p. 23, §21. 
use of, p. 21, § 21. 

S. 

S, description of the letter, p. 53, § 41; p. 66, § 47. 
Scale or rule, p. 3, § 2; p. 29, § 27; p. 32, § 29. 
architects', p. 29, § 27. 
care of, p. 31, § 27. 
choice of, in drawing, p. 93, § 61. 
design of, p. 29, § 27. 
determining the, p. 93, § 61. 
divisions on a, p. 90, § 60. 
drawing, p. 90, § 60. 
engineers', p. 29, § 27. 
flat, p. 29, § 27. 

for several parts on a single sheet, p. 94, § 61. 
machinists', p. 4, § 2; p. 32, § 29. 
most commonly used, p. 91, § 60. 
of a drawing, p. 93, § 61. 
to draw to, p. 90, § 60. 
to read a, p. 91, § 60. 
to test the accuracy of, p. 31, § 27. 
triangular, p. 30, § 27. 
use of, p. 30, § 27. 
Screw thread, p. 72, § p; p. 89, § 59. 

conventionally shown, p. 89, § 59. 
isometric drawing of, p. 163, § 126. 
Screws, cap, p. 128, § 84. 

A.S.M.E. standard, p. 126, § 84. 
machine, p. 126, § 84. 
various forms of, p. 126, § 84. 
Section, a turned-up, p. 83, § 55. 
compound, p. 79, § 55. 
liner, p. 82, § 55. 



INDEX 191 

Section, lines, p. 77, § 54. 

longitudinal, p. 79, § 55. 
transverse, p. 79, § 55. 
Sectional views, p. 79, § 55. 

location of, p. 83, § 55. 
Sectioning adjoining pieces, p. 82, § 55. 
an area, p. 82, § 55. 
and sectional views, p. 79, § 55. 
conventional, p. 79, § 55. 
isometric, p. 164, § 127. 
ordinary, p. 81, § 55. 
spacing of lines in, p. 82, § 55. 
Selection of instruments, p. i, § i. 
Sentences, spacing between, p. 42, § 35. 
Set of free-hand drawing exercises, p. 139, § 100, etc. 

free-hand isometric draAving exercises, p. 167, § 132, etc. 
free-hand lettering exercises, p. 44, § 38, etc. 
mechanical drawing exercises, p. 116, § 79, etc. 
Seven, description of the numeral, p. 58, § 44. 
Shaft, conventionally shown, p. 87, § 59. 
Sharpener, pencil, p. 3, § 2; p. 14, § 13. 
Sheets, operation, p. 85, § 57. 

size and nimibering of, p. 139, § 99; p. i65, § 131. 
title form for, p. 138, § 98. 
Shield, erasing, p. 3, § 2; p. 17, § 16. 
Shrink rule, p. 92, § 60. 
Side elevations, p. 75, § 53. 

Size and numbering of sheets, p. 139, § 99; p. 166, § 131. 
Six, description of the nimieral, p. 59, § 44. 

and lettering of letter sheets, p. 44, § 37. 
and numbering of drawings, p. 103, § 68. 
Sketches, free-hand, from objects, p. 132, § 93. 
on cross-section paper, p. 133, § 
value and use of, p. 131, § 91. 
Sketching, examination in free-hand exercises (see Exercises in Free-hand Drawing 

and Exercises in Isometric Free-hand Sketches), p. 154, §115. 
Sketching from memory, p. 134, § 94. 
dimensioning, p. 132, § 93. 
Sketch sheets, size and numbering of, p. 139, § 99; p. 166, § 131. 

to build up a, p. 137, § 97. 
Slope of fractions, p. 60, § 45. 

letters, p. 36, § 33. 
Sloping ellipse, p. 50, § 40. 
Small or lower-case letters, detail description of {see also Letters), p. 60, § 47. 

spacing of, p. 42, § 35. 
Soapstone, p. 3, § 2; p. 18, § 17. 
use of, p. 18, § 17. 

soda, carbonate of, p. 4, § 2; p. 116 § 78. 
Spacing for various hne-combinations in lettering, p. 39, § 35. 
Speed lathe, perspective of, Frontispiece. 
Sphere, isometric drawing of a, p. 165, § 129. 
Spacing, key or chart for, p. 43, § 35. 

between section Hnes, p. 82, § 55. 
of capital letters, p. 40, § 35. 
of numerals, p. 42, § 35. 
of words and sentences, p. 42, § 35. 
Standard parts, p. 103, § 67; p. 126, § 84. 
Steel scale, p. 4, § 2; p. 32, § 29. 
Structural steel cross-sections, p 90, § 59. 
Studs, p. 127, § 84. 
Square, T-, p. 2, § 2; p. 8, § 10. 
Square thread conventionally shown, p. 89, § 59. 



192 INDEX 

Steel shapes, conventional, p. 90, § 59. 

Stem of letters, p. 37, § 34. 

Strokes, system of, in lettering, p. 38, § 34. 

Study of lettering, p. 34, § 32. 

Sub-dimensions, p. 96, § 62. 

Supplies, list of, p. 2, § 2. 

quality of, p. i, § i. 
Surfaces, finished, p. 98, § 64. 
Symbols on a drawing, p. 72, § 52. 
Symbol for "center hne," p. 78, § 54. 

"inches," p. 95, § 62. 
Systematic method of lettering, p. 44, § 36. 
System, drawing-room, p. 175, Appendix A. 



T, description of the letter, p. 45, § 38; p. 66, § 47. 
T-square, p. 2, § 2; p. 8, § 10. 
care of, p. 10, § 10. 
design of, p. 9, § 10. 
test of, p. 9, § 10. 
use of, p. 10, § 10. 
Table of U. S. standard bolts, p. 127, § 84. 
Tacks, thumb, p. 2, § 2; p. 8, § 9. 
Tail stock, assembly of. Frontispiece. 
Tapers, dimensioning, p. 97, § 62. 
Tapped holes, conventionally shown, p. 90, § 59. 
dimensioning, p. 97, § 62. 
ruling pen, p. 23, § 21. 
Test for T-square, p. 9, § 10. 
triangles, p. 11, § 12. 
Third angle projection, p. 74, § 53; p. 84, § 56. 
Threads, conventionally shown, p. 72, § 52. 
Thread, invisible, p. 89, § 59. 

national acme, p. 89, § 59. 
square, conventional p. 89, § 59. 
V, conventional, p. 89, § 59. 
Threaded piece, dimensioning a, p. 97, § 62. 

portion, length of, p. 89, § 59. 
Three, description of the numeral, p. 59, § 44. 
Threads, forms of, p. 89, § 59. 
Thumb tacks, p. 2 § 2; p. 8, § 9. 

selection of, p. 8, § 9. 
use of, p. 8, § 9. 
Time-keeping in drawing, p. 105, § 71. 
Timber, conventionally shown, p. 87, § 59. 
Title form on a drawing, p. 100, § 66. 

small sheets, p. 138, § 98. 
Titles and headings, design of, p. 69, § 49. 

on a drawing, p. 69, § 49; p. 98, § 65. 
Tracing, p. 114, § 77. 

care of, p. 6, § 6; p. 115, § 77. 
cloth, p. 2, § 2; p. 6, § 6. 

choice of working side, p. 6, § 6; p. 115, § 77. 
to clean, p. 115, § 77. 
to fasten on drawing board, p. 107, § 73. 
use of, p. 6, § 6. 
erasures on a, p. 115, § 77. 
exercises in {see also set of Mechanical Drawing Exercises in, Table of 

Contents, Chapter III), 
paper, p. 6, § 5. 
to make a, p, 114, § 77. 



INDEX 193 



Transverse section, p. 79, § 55. 
Triangle, p. 2, § 2; p. 10, § 11. 

selection of, p. 10, § 11. 

use of, p. 12, § II. 

test for 90° angle of a, p. 11, § 11. 
45° angle of a, p. 11, § 11. 
30° also 60° angle of a, p. 12, § 11. 
Triangular scales, p. 30, § 27. 
Turned-up section, p. 83, § 55. 
Two, description of the numeral, p. 59, § 44. 

U. 

U, description of the letter, p. 52, § 41; p. 65, § 47. 
Upper-case or capital letters {see Letters, Description of). 
U. S. standard bolts, p. 127, § 84. 

V. 

V, description of the letter, p. 46, § 38; p. 67, §47. 

Vertical plane of projection, p. 73, § 53. 

View, plan, front and side, p. 75, § 53- 

Views, arrangement of, p. 75, § 53; P- 83, § 56. 

how to work up, p. 74, § 53; p. 86, § 57; p. 109, § 74. 

number of, p. 83, § 56; p. 103. 

projected, p. 73, § 53. 
Visible hnes, p. 76, § 54. 
V thread, conventional, p. 89, § 59. 

W. 

W, description of the letter, p. 47, § 38; p. 67, § 47. 
Wall, isometric drawing of a, p. 162, § 124. 
Wedge, pencil sharpened to a, p. 16, § 14. 
Weight of lines, p. 76, § 54. 
Whatman paper, p. 5, § 3. 
Wiper, pen, p. 4, § 2; p. 33, § 30. 
Words, spacing between, p. 42, § 35. 
Working drawings, dimensioning, p. 94, § 62. 

X. 

X, description of the letter, p. 47, § 38; p. 67, § 47. 

Y. 

Y, description of the letter, p. 46, § 38; p. 65, § 47. 

Z. 

Z, description of the letter, p. 47, § 38; p. 67, § 47. 



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